Prepare the marinade. Put the trimmed backstrap in it for at least 2 hours, but up 8 hours, in the fridge.
Prepare the dipping sauce, or nam jim jaew. Toast two tablespoons of uncooked sticky rice grains in a pan over low heat while stirring frequently for about 20 minutes. The grains will turn a sandy brown color. Watch it closely near the end, it can turn and burn fast. Transfer to a bowl to let cool slightly. Then grind to a fine powder in a spice grinder or mortar and pestle.
Combine the rest of the sauce ingredients in a small non-reactive bowl or container. I recommend to add the onion, cilantro, and toasted rice powder when you’re ready to serve. Some rice powder will settle on the bottom.
Prepare cabbage/lettuce by separating into single leaves and slice cucumber
Grill the meat until it’s done to your liking. Note that this recipe is best with rarer meats, especially if it’s a lean cut. My preference is 125 degrees F, or blue rare with a nice sear on the outside.
Slice venison thinly, dip in sauce, and wrap with a few spoons of sticky rice in raw cabbage or lettuce leaves. Eat with cucumber slices as needed to cool your mouth.