Heat the oven to 190°C (Gas Mark 5 / 375°F). Toss the diced sweet potato in a dash of oil, and spread it out in a single layer on a baking tray. Season with salt and pepper, and roast for about 10 minutes. Then add the thinly sliced peppers to the tray, mix to combine, and roast for a further 30 minutes or so, until the vegetables are very soft and starting to crisp up and caramelise around the edges.

Add the mayonnaise and pesto to a small bowl, and mix well to combine.

Spread the pesto mayonnaise in a line down the centre of two large flour tortillas. Top with the roasted vegetables (warm or cooled to room temperature), sliced avocado, and a small handful of fresh rocket. Tuck in the ends of each tortilla, and roll tightly. Cut in half to serve.