In a small saucepan, heat beans or lentils with ketchup and curry powder until warm.
Smash with a fork.
Preheat toaster oven or conventional oven broiler.
Spread bean mixture on top of pita bread. Sprinkle with onion, then if desired, top with a dairy or vegan cheese to cover. Place under broiler until cheese melts, watching closely.
Remove to serving plates. Pile sprouts on top, add tomato slices, and serve while hot.