Rinse the bulgar wheat under cold water. Tip it into a heatproof bowl. Pour in 250ml boiling water to cover the bulgar wheat. Pop a saucer over the bowl. Put it to one side to soak.
Pick any large, thick stalks from the watercress. Shred the leaves and smaller stalks.
Peel and finely chop the onion. Finely dice the tomatoes.
When the bulgar wheat is tender and has soaked up the water, add the watercress, onion and tomatoes. Stir in 1 tbsp olive oil. Season to taste.
Pop the beef stir-fry strips in a bowl. Add 1 tbsp olive oil and season. Turn to coat in the oil.
Warm a deep frying pan or wok. Add the beef. Stir-fry for 5-6 mins till it’s brown and cooked.
Add the beef to the tabbouleh. Serve with wedges of lemon for squeezing.