Cut chicken meat into 2 cm pieces, mix with starch, pour over sesame oil and soy sauce, mix well and marinade.
Divide cauliflower and broccoli into florets. First, simmer cauliflower 4 minutes in salted water, then add the broccoli florets and simmer for a further 2 minutes. Strain, rinse cold, and drain well. Peel garlic and ginger and chop finely. Cut spring onions into rings. Core and chop the chilli also fine.
Heat oil over high heat in a wok or frying pan. Add chicken cubes and fry them. Reduce heat and add chili, garlic, onion and ginger. Last add broccili, cauliflower and fry over high heat. Season with salt and pepper. Pour on soy sauce, cooking water, sherry or rice wine.