Cook the rice as per packet instructions, then keep the saucepan covered and leave it to one side.
Meanwhile heat a little oil in a frying pan on a medium to high heat. Once hot, fry the garlic and ginger for 1 minute. Then add in the cauliflower and onion, and fry for a further 5 minutes.
Add the red and green peppers and fry for 2 minutes.
Meanwhile, in a small bowl combine the soya sauce, apple cider vinegar, sugar, tomato puree and add to the frying pan along with the pineapple chunks and pineapple juice.
Next in a small bowl combine the cornstarch with 2 tbsp water then add the mixture to the pan. Cook for 8-10 minutes until the sauce has thickened.
Serve the sweet and sour on a bed of rice.