Heat your oven to 200°C/Fan 180°C/Gas 6. Tip the couscous into a bowl. Pour in 150ml boiling water. Cover with cling film or a plate. Set aside to soak.
Scrub and trim the carrots. Halve or quarter the carrots, depending on how large they are. Tumble into a roasting tin. Halve the pepper, scoop out the seeds and white pith and slice into fingers around 2cm thick. Peel and halve the shallots. Add them all to the tin.
Sprinkle 2 tsp cumin seeds over the veg. Peel and grate in the garlic. Halve the chilli. Scoop out the seeds (or leave them in for extra heat). Finely slice and add them to the veg. Drizzle over 1 tbsp olive oil and add a pinch of salt and pepper. Toss everything together.
Slide the roasting tin into the oven. Roast for 30 mins till the veg are tender and a little charred at the edges.
While the veg roasts, finely grate the zest from the lemon. Pop it in a bowl. Squeeze in the juice from half the lemon. Add ½ tbsp olive oil and a pinch of salt and pepper. Whisk together to make a dressing. Set aside.
Finely chop the parsley leaves and stalks. Warm a frying pan over a high heat for 2 mins. Add ½ tbsp olive oil to the pan with the beef stir-fry strips. Stir fry for 3-4 mins till browned all over.
Take the veg out of the oven. Add the couscous, most of the parsley and all the watercress. Pour in the salad dressing. Toss to mix together. Pile the salad onto 2 warm plates and top with the beef and the remaining parsley to serve.