In a large bowl, dissolve sugar in 1/2 cup warm water, then add soy sauce, rice wine vinegar, ketchup, lemon juice and sesame oil. Mix well and throw in the fridge until you’re ready to eat.
Just before serving, combine 1 teaspoons hot water with dijon mustard and garlic and mix in small bowl. Add to the pouring sauce, 1/2 a teaspoon at time to taste.
2To make the stir-fry sauce:
Prep the stir fry sauce by mixing soy sauce, brown sugar, and rice vinegar in a small bowl.
3To make the chicken stir-fry:
Combine oils and add to wok or large frying pan. Heat oil over high heat until it glistens, about one minute. Add chicken and saute until mostly cooked through, about 5 minutes.
Turn the heat under the wok down to medium-high. Add another tablespoon of olive oil to the pan, wait one minute, and then add garlic, onions, water chestnuts, mushrooms, and the stir-fry sauce you prepared earlier. Stir-fry everything until the mushrooms have cooked through, about 4 minutes, and remove to a serving dish.
Serve stir-fry with iceberg lettuce or nappa cabbage leaf wraps and top with pouring sauce.