Line 2 baking sheets with parchment paper. Combine the ground beef, bread crumbles, milk, cilantro, parsley, chili powder, cumin, salt, garlic powder, onion powder, pepper and eggs in a large mixing bowl. Mix together well with your hands. Scoop out 1-tablespoon portions, then place 1 piece of cubed pepper jack into each portion and roll them into balls with your hands. Place the meatballs on the lined baking sheets and freeze for the meatballs to firm up, 10 to 15 minutes.
Heat the olive oil in a heavy pot or large skillet over medium-high heat. Add the meatballs in 5 batches of 25, making sure not to overcrowd the pot. Cook, turning the meatballs to make sure they brown all over, 5 to 7 minutes per batch. Drain on paper towels. Serve over rice, in tacos or as appetizers, recipes follow.
To freeze: Put the cooked meatballs in a single layer on lined baking sheets and put in the freezer. Once frozen, divide them into freezer bags, about 25 per bag, and return them to the freezer.
To reheat: Place the frozen meatballs on a baking sheet and bake in a preheated oven at 350 degrees F for 15 minutes.
For meatballs over rice (8 servings): Divide 2 cups cooked rice among 8 serving plates. Top with 3 meatballs each, then spoon on 2 tablespoons salsa and 2 tablespoons sour cream on each. Sprinkle with chopped cilantro and add a wedge of lime to each plate.
For meatball tacos (8 servings): Warm 8 large soft corn tortillas in a microwave, about 30 seconds. Put one on each serving plate, then top each with 2 tablespoons shredded iceberg lettuce, 3 meatballs, 2 tablespoons grated Cheddar and 2 tablespoons pico de gallo. Fold up and serve.
For meatball appetizers (25 meatballs): Pour 1 1/2 cups guacamole into a bowl. Put the bowl on a platter and surround the bowl with 25 meatballs. Stick toothpicks into some of the meatballs. Put some spare toothpicks in a container and put on the platter. Garnish with cilantro leaves.