Paneer Tikka Sandwich

Heat oil in a large skillet over medium heat. Add onions; cook and stir until softened, about 5 minutes. Stir in chile powder, garam masala, turmeric, sugar, and salt. Add paneer and tomato sauce; cook and stir until flavors combine, 3 to 5 minutes.

Spread 1 teaspoon butter and 2 tablespoons of the paneer filling over 1 slice of bread. Place second slice of bread on top.

Melt remaining 1 teaspoon butter in a large skillet over medium heat. Add sandwich; cook until golden brown, about 1 minute per side.