Put the minced beef in a bowl. Dice the onion finely. Heat the oil in a pan over medium heat, add the onion, and cook for 5 minutes until translucent. Transfer the onion to a plate and let cool for 2-3 minutes.
Finely chop the fresh chili peppers and fresh bell pepper. Add them to the minced beef along with the eggs, breadcrumbs, mustard, ketchup, kidney beans, corn, paprika powder, and cooled onions. Mix well with your hands until combined. If the mixture is too wet, add more breadcrumbs.
Season the mixture with salt and pepper to taste. Add cayenne pepper if desired for extra heat.
Form the mixture into meatballs of roughly equal size.
Brush the meatballs lightly with oil. Heat a grill pan or regular pan over medium-high heat, add the meatballs, and cook for 15-20 minutes, turning occasionally, until cooked through (internal temperature 71 °C / 160 °F). For best results, cook on a grill.