Heat beef if using leftovers. Otherwise, brown in a medium skillet over medium heat. Drain grease if necessary, and season with salt and pepper to taste.
While beef is cooking, chop bell pepper and shred lettuce.
In a small dish, mix yogurt with taco seasoning and spread evenly onto each tortilla.
Top each with beef, chopped pepper, and shredded lettuce; roll up.
Serve with broccoli, cauliflower, and mango on the side.