Stew

I have a loose vegetarian stew recipe that I have made up that is wonderful in the sense that it is flexible and quick. It does have one constant, in that it has a tomato base. What can I sub the tomato content with? The recipe usually involves sauteing up some garlic or onions, throwing in a can of chopped or crushed tomatoes (pre-seasoned, or unseasoned) adding in a couple cups of legumes (chickpeas or lentils usually) then whatever...