1. Mix ground pork, garlic, fish sauce, soy sauce, sugar, and black pepper in a bowl. Form into 4 patties.
2. Grill patties over medium heat for about 5 minutes per side, until cooked through.
3. In another bowl, mix rice vinegar, water, sugar, and salt. Add carrots and daikon radish. Let sit for at least 15 minutes.
4. Toast burger buns on the grill.
5. Assemble the burgers: Spread mayonnaise on the buns, add a pork patty, pickled vegetables, cucumber slices, cilantro, and jalapeño slices. Top with the other half of the bun.