Stir Fry Prawns in Tomato Sauce

INGREDIENTS:
-1 pound prawns
-1 teaspoon cornstarch dissolved in 3 tablespoons water
-3 tablespoons oil for stir-frying, or as needed
-1 tablespoon garlic, chopped
-1 tablespoon ginger, chopped
-1 tablespoon french onion, chopped
-Half a green capsicum
-1 tablespoon rice wine
-4 tablespoons catsup
-1/2 teaspoon salt
-1 teaspoon sugar

DIRECTIONS:
1) Wash and devein prawns.
2) Prepare water/cornstarch mixture.
3) Heat wok. When hot, add three tablespoons oil.If adding vege, add them now, stirring while you add them.Stir-fry vegetables for about one minute, then push them up to the side of the wok and add the prawns.
4) Mix well.When prawns have turned pink (very quick), add garlic, ginger and green onion, and rice wine and catsup, stirring all the while.
5) Add the salt and sugar.
6) Give the water/cornstarch mixture a quick restir, and pour it in.Stir.
7) If you like, you can a bit of chicken broth at this point to season