Trim and finely slice the chilli (deseed if you like). Deseed and dice the tomatoes, then mix with most of the chilli and a lug of oil. Season with a pinch of sea salt.
Place a pan on a medium-high heat. Drain and rinse the chickpeas, then tip into the pan, stirring until warmed through. Season with salt and black pepper, then finely grate in half the lemon zest, and drizzle over a lug of oil.
Tip the chickpeas into a food processor and pulse until smooth, or mash by hand, then stir in the tomato mixture.
Preheat a griddle pan to high. Slice the chorizo at an angle, about 5mm thick, then griddle for 3 to 5 minutes, or until charred around the edges.
Halve the rolls and fill with the chickpea mixture and grilled chorizo. Add the rocket leaves and sprinkle with the remaining chilli slices, then tuck in.