There is no direct replacement for tofu. It depends on how it's used. If tofu is cubed and tossed onto something (like a salad or stir-fry), you can omit it or replace it with your favorite beans, chickpeas, or lentils. If the tofu is being used to cook something, it gets more tricky to find substitutes. If the recipe calls for silken tofu (soft tofu), you can try using yogurt. If a firm or extra firm tofu is being used in a recipe, you could try mashed beans or chickpeas, lean meat, lean fish, and seafood (as a protein source) would work well. It is very important to get animal and plant-based protein with food.