Saute in non-stick pan on low heat the black beans, corn, onions, jalapeno, cumin, and chili powder for about 5 minutes. Remove and add to a bowl and add lime juice. Smash beans lightly with a potato masher or back of a fork. Next add avocado and mix in. Place mixture in refrigerator for about 10 minutes to cool. Place filling in the egg roll wrappers and follow directions on the back of the egg roll wrapper package on how to fold. Remember to add salt and pepper to taste.
Heat up 2 tablespoons of olive oil in large frying pan. Cook egg rolls until crispy brown on each side.
Dipping sauce: Place sour cream, tomatoes and a large handful of cilantro into a food processor/blender and blend until smooth. Add salt and pepper to taste.