Trim excess fat from meat and slice thinly against the grain. Combine marinade ingredients and marinate meat in a bowl or zipper bag for a minimum of 30 minutes or up to 24 hours.
3 lbs flank steak, ⅔ cup soy sauce, 1 tablespoon garlic, 2 teaspoon paprika, 1 teaspoon ground ginger, ⅔ cup vegetable oil
Before cooking, use a strainer to drain meat well. Reserve the marinade for the sauce.
Spray a skillet lightly with non-stick spray or oil and heat over medium-high. Add meat in a single layer and allow to cook until browned and almost cooked through, stirring minimally, 7-8 minutes. If meat does not fit in a single layer, cook in two batches. *If meat releases a lot of juices while cooking, remove it from the pan, pour juices out of pan into reserved marinade, and return the meat to the pan to continue cooking. Remove meat from pan. Add 1 tablespoon vegetable oil and cook bell peppers and celery. Cook until tender-crisp, 3-5 minutes.
3 medium bell peppers, 1½ cup celery
In a small bowl, mix water and cornstarch together. Add water mixture, reserved marinade juices, and cooked meat back to the skillet with the veggies. Cook until the sauce is thickened, 1-2 minutes.
1½ cups water, 2 tablespoon cornstarch
Stir in fresh tomatoes and salt, if needed. Serve over rice.
2 cups fresh tomatoes, Salt