Make the marinade by mixing together the sugar, salt, soy sauce and cornflour slurry. Mix in the minced pork, let marinate for 20 minutes.
Meanwhile, blanch the carrots in boiling water for 3 minutes. Add the celery and blanch for 1 minute. Drain well and set aside.
In a small bowl, mix together the tomato ketchup, 150ml sugar and salt to make the sauce. Set aside.
Heat a large frying pan with 1 tablespoon oil over high heat. Stir-fry the pork until cooked through, 4-5 minutes. Set aside.
In the same frying pan, heat 1 tablespoon oil over high heat. Stir-fry the garlic until fragrant, 2-3 minutes. Add the onions with 1 teaspoon salt, cook until soft, 3-4 minutes. Add carrots and celery, stir well. Add pork, tomatoes and water. Stir, cover and simmer for 2-3 minutes. Stir in the sauce and serve.