Lamb burger and sweet potato chips

• Peel the sweet potatoes and cut them into thick chips. Mix them in a bowl with the oil, spices and breadcrumbs. Spread them out in a single layer on a baking tray and bake for 35 minutes at 220°C, stirring once or twice.

• Meanwhile, finely blend 1 red onion with the peeled ginger, the coriander stalks, 2 tablespoons of yoghurt and 1.5 teaspoons of salt. Add the meat and pulse the mixture until everything is well combined. Shape into 4 thick patties and set aside in the fridge.
• Blend half the coriander leaves with the rest of the yoghurt, salt, pepper and 2 tablespoons of olive oil. Set aside in the fridge.
• Remove the seeds from the tomatoes and dice them finely. Mix them with the rest of the chopped coriander leaves and the finely sliced red onion. Season with salt and pepper and add 2 tablespoons of olive oil.
• Cook the steaks over a low heat for 5 minutes on each side in a little oil.

• Lightly toast the buns, split in half, brush with yoghurt sauce, place the cooked steaks on top, then add the tomato salad. Serve with the chips and the remaining sauce.