In a bowl, mash the chickpeas with a fork, leaving a few whole beans for texture.

Stir in Greek yogurt, lemon juice, dijon mustard, sunflower seeds, and season with salt and pepper to taste.

Toast the bread if desired. Spread the chickpea mixture on the bottom slice of bread, top with greens, and add the top slice. Serve.

Meal Prep Note: Store chickpea mixture in an airtight container in the fridge for up to 3 days. Store greens and bread separately. For the best texture, assemble the sandwich just before eating.