Ingredients

Step by step

1. Preheat the barbecue. Use a large, sharp knife to cut the sweet potatoes into 12 x 1cm thick rounds, putting the ends to one side – see Kitchen Secret. Score each round with a criss-cross pattern on both sides. Rub all over with olive oil, season with salt and pepper and a few of the chilli flakes, if you like.
2. Cook the sweet potato rounds on the cooler part of the barbecue for 20-30 minutes, turning halfway, until tender and cooked through. Alternatively, you can bake them in a preheated oven (220°C, fan 200°C, gas 6) for 25-30 minutes.
3. Meanwhile, halve and stone the avocados, roughly mash the flesh with a little salt on a chopping board using a fork, add the rest of the chilli flakes, if using, or black pepper if not, and lemon juice to taste. Finely chop a handful of rocket leaves; stir into the avocado.
   Tip

   Roast any leftover sweet potato ends and add to salads, or mash and serve with barbecued meat – toss with a little olive oil and season, then roast for 20-30 minutes until completely tender.
4. Halve the brioche buns; toast cut-side down on the barbecue for a minute or so until griddle marks appear.
5. When the sweet potatoes are cooked, you're ready to assemble. Spread a quarter of the rocket and avocado mash over each bun base, top each with a few rocket leaves then layer up 3 rounds of sweet potato with crumbled Stilton in between. Finally add the brioche bun top and secure with a cocktail stick if you like.