Heat oven to 375 degrees.
Heat oil in skillet over medium heat. Add peppers, onions and tomatoes. Cook 3 to 4 minutes, or until tender. Add black beans and taco seasoning. Cook 2 minutes. Set aside to cool.
Lay empanada dough out on parchment-lined baking sheet. Fill with black bean filling and 1 tablespoon cheese. Fold dough over filling to create pocket. Use fork to press down sides to seal. Brush with egg whites. Repeat with remaining dough, filling, cheese and egg whites.
Bake 20 to 25 minutes, or until golden brown. Remove from oven and let cool.
Serve two empanadas with guacamole (or mashed avocados) for dipping, and the fruit and veggies on the side.