In a small bowl, combine the cornstarch and water. Mix thoroughly and leave to dissolve while you make the sauce.

In a small saucepan, combine the ketchup, soy sauce, sugar, vinegar, pineapple juice, salt, and red pepper flakes. Bring to a boil, reduce heat, and simmer for about 10 minutes. Remove from hear and immediately stir in the cornstarch mixture. Set aside.

Begin heating your oil in a medium skillet and filling it up about 1/4 inch. You want the oil to reach roughly 375 degrees F.

In a shallow bowl, whisk together the flour, salt, and pepper. Dip each piece of tofu in the flour mixture and set aside until the oil is ready.

Once ready, fry the tofu for 2-3 minutes on each side, remove from pan, and let cool slightly on a paper towel to soak up the excess oil. Repeat until all of the tofu has been fried.

Once cooled slightly, toss the tofu (and the pineapple if using) in the sauce. Serve over your prepared rice and ENJOY!! This is also great served with some lightly sautéed bell peppers and onions!