Heat oil in large skillet on high.
Add onion, bell peppers, garlic and jalapeno (if desired) to skillet and cook until tender.
Add ground beef and cook until crumbly. Drain grease (if any).
Add taco seasoning, salsa, corn, black beans and tomatoes.
Bring to boil, and then reduce heat to a simmer. Stir constantly for approximately 5 minutes.
Remove pan from heat. Add cheese on top and bake at 350 for 8-10 minutes or until cheese is completely melted.
Add green onions and avocado as optional garnishes.
Serve warm with tortilla chips.