My favorite stir fries are started by cooking tofu to a tasty, chewy texture. Tofu does not have much flavor on its own, but absorbs the flavor of what it is cooked with.
Cut a firm block of tofu in to 1/2 X 1/2 inch wide by 1/4 inch thick pieces, and drain well. In a well seasoned cast iron pan heat 1 - 2 tablespoons olive oil to medium - high temperature. Add tofu. Allow the tofu to brown stirring often. As it cooks the moisture be reduced and it will gain a chewy texture.
Once the tofu is cooked, I add the stir fry veggies in endless combinations. Last, but not least, add the seasoning and sauces.