Toss pork cubes in mixture of soy sauce and 1 tbsp. oil. Marinate for about 15 minutes.
In a large frying pan, sauté garlic clove in 2 tbsp. oil over medium high heat until brown. Brown pork cubes in the garlic flavoured oil, then reduce heat and cook about 5 minutes longer, stirring often.
Sprinkle lightly with salt and pepper. Add onions and green pepper and stir fry for 2 to 3 minutes.
While meat and vegetables are cooking, make the sauce in a small saucepan. Mix together sugar, cornstarch and salt. Stir in vinegar, water and tomato paste. Bring to a boil, stirring until smooth and clear.
Drain any excess fat from the frying pan. Add the sauce to the pork and vegetable mixture and simmer for a minute. Taste and adjust seasoning if necessary.
Add drained peaches and tomato. Cover pan and cook gentle just until heated through.