Merguez sausage, roast potato and aïoli baguettes

Method

1. Heat the oven to 180°C/160°C fan/gas 4. Peel the potatoes and cut into small chip-like wedges. Rinse well, put in a large pan, cover with cold water and season with salt. Bring to the boil, then simmer the potatoes for 3-4 minutes. The outside of them should be soft and the insides still just undercooked. Drain the potatoes in a colander and leave to steam dry for 5 minutes.
2. Put the duck or goose fat in a large roasting tin and put over a medium heat on the hob (if your roasting tin won’t go on the hob, heat in the oven for 5-6 minutes). Tip the potatoes into the roasting tin and season with salt and pepper. Break the cloves from the garlic bulbs and bash each clove with the side of a large knife. Add them to the tin with the rosemary and gently toss everything to coat in the fat. Roast for 1-1½ hours, turning every 20 minutes or so, until crisp and golden.
3. Meanwhile, make the aïoli. Put the garlic and salt in a mini food processor and pulse briefly. Add the mustard, 1 tsp lemon juice and the egg yolks, then whizz until smooth. Combine the oils in a jug and slowly drizzle into the egg yolk mixture while the motor is running. The mixture should form a thick emulsion. If the emulsion becomes too thick, add a tiny splash of warm water. Season to taste with salt, lemon juice and black pepper, then set aside.
4. Heat a griddle (or frying) pan over a medium-high heat. Brush the merguez sausages with a little oil, then grill on each side for 5 minutes until cooked through.
5. Split the baguettes open and smear each with a tablespoon of aïoli. Wedge 3 merguez sausages into each baguette, then press in a small handful of roast potatoes (put any extra in a bowl and serve alongside with the remaining aïoli). Eat straightaway, with plenty of paper napkins to hand – the juices from a merguez sausage have impressive staining qualities.