Dice chicken breast and keep it aside. Prepare the batter by mixing cold water and flour in a bowl, stirring well to avoid lumps. Add the chicken to the mixture, stir until the meat is completely covered by the batter and leave aside for a few minutes. In the meantime, heat up a wok over a medium fire (you can also use a deep pot or pan), add 1 Lt of peanut oil and heat it up for five minutes, (you can drop a Tsp of batter in the oil to check when is ready to fry). Start frying the chicken 3/4 pieces at the time until golden brown and set aside on kitchen tissue to absorb any oil in excess. Cut up all the vegetables then heat the wok oil in another wok or pan, add all the diced veggies and cook for 5 minutes, stirring well until all vegetables are cooked on the outside but still crispy inside. Stir in cherry tomatoes and diced pineapple, mix well adding sweet n sour sauce, oyster sauce, wok sauce, rice vinegar, salt and sugar. Cook for another couple of minutes and finally stir in the chicken that we have previously deep fried. Stir for another 2 minutes until well combined. Serve garnished with cashew nuts, sesame seeds, spring onion and rice.