Heat 2 teaspoons of the oil in a wok or large non stick pan over high heat. Add half the chicken in a single layer. Let it sit undisturbed for 30 to 60 seconds to lightly brown, then stir fry until just cooked. Transfer to a plate. Repeat with the remaining chicken.
Heat the remaining oil in the pan. Add the onion and stir fry for 1 minute. Add the curry powder and sugar and stir to combine. Return all the chicken to the pan and cook for another minute.
Add the peanut butter and Jimmy’s Saté Sauce. Stir well to coat. Gradually add water, stirring, until the sauce reaches your desired consistency (you may not need it all).
If using broccoli, add it now and stir until heated through. Serve with steamed rice and garnish with sliced spring onion if desired.