Sweet sour sauce

Ingredients

• 2 tablespoons peanut oil
• 1 clove garlic
• 1/2 cup water chestnuts
• 1 red capsicum
• 1 small onion
• 3 tablespoons peas
• 1/4 teaspoon fresh ginger
• 1 tablespoon light soy sauce
• 3 tablespoons tomato sauce
• 2 tablespoons white vinegar
• 2 tablespoons sugar
• 3/4 cup water
• 1 tablespoon cornflour
• 1 tablespoon water
• 2 tablespoons preserved melon shreds