Heat the oven to 200C/180C/gas 6. Put the oil and sweet potatoes on a baking tray and toss with seasoning. Roast for 15-20 mins. Add the cherry tomatoes and broccoli, then toss with the sweet potatoes. Roast for 15 mins more until the tomatoes are close to bursting.
Nestle the salmon in the tray, brush with 1 tbsp of the tahini and top with the sesame seeds. Bake for a further 8-10 mins until the salmon is cooked through. Loosen the remaining tahini with a bit of water if needed, then drizzle over the cooked veg and serve.