Step 1Heat a grill or grill pan to medium-low heat. Wrap the shrimp paste in a double layer of foil and enclose the packet. Grill the foil packet for 2 minutes; the paste should be very fragrant. Let cool, then unwrap.
Step 2While the shrimp paste cools, pound the shrimp, garlic and chiles in a mortar with a pestle until smashed into tiny bits. Or you can pulse the ingredients in a food processor. Add the palm sugar and shrimp paste and continue pounding or pulsing to form a coarse purée. Add ¼ cup lemon juice and stir or pulse until incorporated. Taste and add up to ¼ cup more lemon juice to taste.
Step 3Transfer to a serving dish and serve with crudites.