In a small bowl, mix together yogurt and curry powder. In a medium mixing bowl, mash chickpeas with a fork until they are a bit crumbly, some chunks are okay. Add carrots, bell peppers and curried yogurt to chickpeas, stir until well combined. Add salt and pepper to taste. Scoop equal amounts of mixture onto 4 slices of bread. Add desired garnishes and then top with remaining slices of bread.