Make the marinade by mixing together the sugar, salt, soy sauce and cornflour slurry. Mix in the beef, allow to marinate for 15 minutes.
Heat a large frying pan with 1 tablespoon oil. Stir-fry the garlic until aromatic, 2-3 minutes. Add the beef and stir-fry until 70% done, about 3-4 minutes, set aside.
Heat the same frying pan with 1 tablespoon oil. Stir-fry the onion and shallots with 1/4 teaspoon salt until soft, 3-4 minutes. add the tomatoes, tomato ketchup, tomato puree and stir for 2-3 minutes. Adjust the seasoning accordingly.
Bring the sauce to the boil. Add the beef, stir to combine and serve.