Pla Som is a lightly fermented fish dish from Northeastern Thailand, where freshwater fish is mixed with cooked jasmine rice and garlic to develop a gentle sourness.
For more Isaan fermented recipes, try Sai Krok Isaan, a smoky fermented sausage with garlic and rice, Nam Sausage (Som Moo), sour fermented pork, sliced and ready to snack, and Nam Tod, a crispy fried fermented pork salad with herbs and lime.
Pla Som pairs beautifully with Sticky Rice and Som Tum Isaan for a true countryside meal. Explore more Northeastern Thai flavors in my Isaan Food Guide.
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What Is Pla Som
Pla som is a lightly fermented fish dish from northeastern Thailand. Freshwater fish is mixed with cooked jasmine rice and garlic, then fermented briefly to develop a gentle sourness. Unlike long fermented fish products, Pla Som is always cooked before eating, most often fried. This method creates a clean, savory flavor that’s tangy but not overpowering.
Ingredients for Pla Som
Fermentation Ingredients
- Freshwater fish. Tilapia, red snapper or catfish cut into 2 inch pieces. Mild, accessible, and traditional for Pla Som.
- Cooked jasmine rice. Fully cooked and completely cooled. This feeds the fermentation and creates gentle sourness.
- Garlic. Pounded or finely minced for aroma and natural preservation.
- Salt. Essential for flavor and proper, controlled fermentation.
For Frying
- Oil. For frying the whole fish or fish pieces until golden.
- Rice flour. About ⅓ cup for light coating. All purpose flour works as a substitute.
- Egg. One egg for dredging before coating in flour.
Garnishing Options
- Fresh Thai chilies. Chopped for heat.
- Shallots. Thinly sliced for sharp freshness.
- Lime. Cut into wedges for squeezing over the fish.
- Dried chilies. Optional for extra heat.
Why Jasmine Rice Is Traditional for Pla Som
Jasmine rice is traditionally used to start Pla Som fermentation, while sticky rice is served on the side. It ferments clean and even, giving a gentle sourness and balanced texture during the short two to three day ferment.
How to Make Pla Som
- Clean the fish. Rinse the whole fish quickly, remove the guts and gills if needed, then pat completely dry with paper towels. The fish must be clean and dry for proper fermentation.
- Pound the garlic. Using a mortar and pestle, pound the garlic into a rough paste. You want it smashed and aromatic, not perfectly smooth.
- Mix the fermentation base.In a bowl, combine cooked and cooled jasmine rice, pounded garlic, and salt. Mix well until evenly distributed.
- Coat the fish. Rub the rice mixture all over the fish, including inside the belly cavity. Press it in well so every part is covered.
- Pack tightly. Place the coated fish on a plate and press more rice mixture around it. Then transfer to a zip top bag or airtight container. Press out as much air as possible and seal tightly.
- Ferment. Leave at room temperature for 2 to 3 days. When ready, it will smell mildly sour and garlicky, never rotten. Once fermented to your liking, move it to the refrigerator to slow down further fermentation.
Cooking Pla Som
- Pla Som is almost always cooked, never eaten raw. Pan fry it in oil until golden and cooked through, or shallow fry for crisp edges. You can also grill it over charcoal for a deeper, smoky flavor.
- Transfer to a plate and top with sliced chilies. Serve with sticky rice, lettuce or cabbage, fresh herbs, shallots, dried chilies and lime wedges for squeezing over the top.
How To Eat Pla Som
Tear off a piece of the fish and place it over sticky rice or a crisp lettuce leaf. Add sliced shallots, fresh chilies, and a squeeze of lime. Eat it with your hands if you want. That is the best way.
A Quick Fermentation Safety Note
- The rice should be fully cooked, cooled, and slightly dry. Day old jasmine rice works best and ferments more evenly.
- Pla Som is a short ferment, just two to three days. Use very fresh fish, measure your salt carefully, and keep it sealed in a clean container. It should smell lightly sour and garlicky, never rotten. If it feels off, toss it.
- What Pla Som Tastes Like. Pla Som has a mild, pleasant sourness that is not overpowering. It is garlicky, savory, and lightly fermented, similar to sour sausage but cleaner and more delicate. Always cook Pla Som fully before eating.
Storing Leftovers
Store cooked Pla Som in an airtight container in the fridge for up to three days. Reheat in a pan until warmed through and slightly crisp again. I do not recommend refreezing after it has been fermented and cooked.
More Isaan Recipes You'll Love
- Pla Pao. Grilled salt crusted fish with smoky, tender flesh and simple Thai seasoning.
- Moo Tod. Crispy Thai fried pork, juicy inside and golden on the outside.
- Larb Moo. Bright minced pork salad with lime and toasted rice.
- Som Tum Pu Pla Ra. Spicy green papaya salad with bold countryside flavor.
- Nam Tok Moo. Grilled pork salad with herbs and roasted rice powder.
FAQs
No. Pla Som should always be fully cooked before eating.
Mildly sour and garlicky. It should smell clean, not rotten or overly sharp.
You can freeze it before fermentation. After fermenting, it is best to cook it first, then refrigerate and eat within a few days.
Yes. Firm white fish works best. Just make sure it is very fresh.
Related and Pairing
Looking for other recipes like this? Try these: These are my favorite dishes to serve as a complete Isaan Meal.
Pla Som (Isaan Fermented Fish)
- Total Time: 30 minutes, Ferment 2 to 3 days
- Yield: 1 whole fish, serves 2-3 1x
- Diet: Dairy-Free
Description
Pla Som is a lightly fermented fish dish from Northeastern Thailand, where freshwater fish is mixed with cooked jasmine rice and garlic to develop a gentle sourness.
Ingredients
For Fermentation
- 1 pound whole fish
- 1 cup cooked jasmine rice, cooled
- 7 to 8 cloves garlic, pounded or finely minced
- 1 tablespoon salt
For Cooking
- 1- 2 cups oil for frying
- ⅓ cup rice flour or all purpose flour
- 1 egg
For Garnish - As needed
- Fresh Thai chilies, chopped
- Lime slices or wedges
- Shallots, sliced
- Dried chilies
- Lettuce or cabbage
Instructions
- Clean the fish. Rinse the whole fish quickly, remove the guts and gills if needed, then pat completely dry with paper towels. The fish must be clean and dry for proper fermentation.
- Pound the garlic. Using a mortar and pestle, pound the garlic into a rough paste. You want it smashed and aromatic, not perfectly smooth.
- Mix the fermentation base.In a bowl, combine cooked and cooled jasmine rice, pounded garlic, and salt. Mix well until evenly distributed.
- Coat the fish. Rub the rice mixture all over the fish, including inside the belly cavity. Press it in well so every part is covered.
- Pack tightly. Place the coated fish on a plate and press more rice mixture around it. Then transfer to a zip top bag or airtight container. Press out as much air as possible and seal tightly.
- Ferment. Leave at room temperature for 2 to 3 days. When ready, it will smell mildly sour and garlicky, never rotten. Once fermented to your liking, move it to the refrigerator to slow down further fermentation.
How To Cook Pla Som
- Pla Som is almost always cooked, never eaten raw. Pan fry it in oil until golden and cooked through, or shallow fry for crisp edges. You can also grill it over charcoal for a deeper, smoky flavor.
- Transfer to a plate and top with sliced chilies. Serve with sticky rice, lettuce or cabbage, fresh herbs, shallots, dried chilies and lime wedges for squeezing over the top.
Notes
- The rice should be fully cooked, cooled, and slightly dry. Day old jasmine rice works best and ferments more evenly.
- Pla Som is a short ferment, just two to three days. Use very fresh fish, measure your salt carefully, and keep it sealed in a clean container. It should smell lightly sour and garlicky, never rotten. If it feels off, toss it.
- Always cook Pla Som fully before eating.
- Prep Time: 20 minutes
- Cook Time: 10 to 12 minutes
- Category: Isaan food, Isaan recipes
- Method: fermentation, Frying
- Cuisine: Thai
Hi there, I’m Suwanee!
I’m the person behind this Thai food blog. I spent the first thirteen years of my childhood in Thailand, where I fell in love with the flavors of Thai cooking. What started as sharing recipes from my kitchen has grown into a journey from home cook to restaurant chef — and now one of just eight contestants chosen nationwide for PBS’s The Great American Recipe, Season 4. You’re in the right place if you love to cook Thai food. Come by often, and let’s get cooking!
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