Instructions:
1. Place aji paste, apple cider, brown sugar, ketchup, garlic, lime juice, and cumin in a small saucepan. Whisk to combine and bring to a low simmer over medium heat, whisking frequently. Simmer BBQ sauce for 3 minutes then remove from the heat.
2. Portion ground beef into 4 equal patties and season with salt. Preheat a gas grill or prep charcoals for a charcoal grill.
3. Once the grill is hot, add burgers and grill on one side until charred, about 1-2 minutes. Flip the burgers and baste each with 2 tablespoons of BBQ sauce. Continue to cook the burgers for 2-3 minutes or until desired doneness. Top each burger with cheese during the last minute of the cooking time to melt (optional).
4. Remove burgers from the grill and set aside.
5. In a medium bowl, place corn, onion, tomatoes, lime juice, and olive oil, toss to combine.
6. Spread remaining BBQ sauce onto buns and top with burgers, relish, and sliced avocados before serving.