Cut pressed tofu into 1/2 inch slices. Place in a single layer in a small pan and pour tamari over strips. Marinate in tamari for 15 to 60 minutes, turning occasionally to coat evenly. The longer the marination time, the stronger the flavor. Drain.
Heat vegetable oil in a skillet and fry tofu on both sides until lightly browned. Dip fried tofu strips in a bowl of sweet and sour sauce to coat both sides.
Lay strips in a single layer in a heavy baking pan or casserole dish. Bake at 400° F, on the lowest oven rack for 10 minutes. Turn strips with a spatula and bake an additional 10 to 15 minutes until the sauce is well baked in.
If desired, cut slices into 1" cubes. Serve hot with extra sweet and sour sauce on the side for dipping.
Note: If you wish to make this a lower fat recipe, use a non-stick skillet on medium heat and reduce the oil. Start out with 2 teaspoons and only add more oil if the tofu is sticking to the skillet.