1. 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.
2. Pound the garlic. Using a mortar and pestle, pound the garlic into a rough paste. You want it smashed and aromatic, not perfectly smooth.
3. Mix the fermentation base.In a bowl, combine cooked and cooled jasmine rice, pounded garlic, and salt. Mix well until evenly distributed.
4. 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.
5. 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.
6. 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

1. 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.
2. 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.