Pre-heat your oven to 220ºC/200ºC fan.
Roughly chop your red peppers and toss them in 1 tsp olive oil. Roast for 30 minutes (turning halfway through the cooking time) in the oven.
(Skip this step if using tahini) While the peppers are cooking, toast the sesame seeds. Place a small frying pan on a medium heat and once hot add the sesame seeds (1½ tbsp) and cook until light brown, shaking them gently to help them to brown evenly (don't overcook them as that will give them a bitter flavour). Once they're browned immediately remove them from the pan (as the residual heat may burn them) and then grind them into a fine powder using a pestle and mortar or spice grinder.
Once the peppers are cooked, set them aside to cool while you prepare the remaining hummus ingredients. Start by draining the chickpeas and if you've got a bit of spare time peeling them too (it gives you a smoother hummus).
Place them into a blender (or a large bowl if you're using a stick blender) and add the other ingredients (roasted red peppers, ground sesame seeds, 1 tbsp olive oil, 1 clove of garlic, juice of ½ a lemon and ½ a red chilli - I add mine with the seeds still inside).
Blitz the ingredients until smooth. You should find that it has a nice smooth texture but if it seems a little stiff add a little water to help loosen it. Season with salt (and then blend it again to make sure it's evenly distributed) and serve.