Look for plantains that are just beginning to turn black.
Cook beef in a large nonstick skillet over medium-high heat until browned, stirring to crumble. Add garlic, bell pepper, and plantain; cook for 3 minutes. Add tomatoes and next 4 ingredients (tomatoes through black pepper); cook 5 minutes, stirring occasionally.
Heat the tortillas according to package directions. Spoon 1/2 cup meat mixture onto each tortilla; top each with 1/4 cup lettuce, and roll up.
This was really good! It was very similar to a normal taco. The plantain didn't do much for flavor, but the potato texture of it was a nice addition. Also, the green olives are what really make the flavor unique!