Using a sharp knife, carefully cut the chicken in half along the backbone.
Pick the thyme leaves into a pestle and mortar, peel and add 1 garlic clove, then add the paprika and a pinch of sea salt. Bash to a paste, then muddle in 2 tablespoons of olive oil.
Rub the marinade all over the chicken, making sure to get into all the nooks and crannies. Cover and place in the fridge to marinate for at least 2 hours, preferably overnight.
When you’re ready to cook, preheat the oven to 180ºC/350ºF/gas 4. Place a large griddle pan over a high heat.
Quarter the unpeeled onions and halve any larger tomatoes, then place on the hot griddle with the chillies and the remaining unpeeled garlic cloves. Grill for 5 to 10 minutes, or until charred all over, turning regularly.
Remove the garlic skins and peel the onions, then add all the vegetables to a food processor with a splash of red wine vinegar and a good lug of extra virgin olive oil. Blitz until smooth, then add a splash of water to loosen, if needed. Season to taste.
Return the griddle pan to a high heat, add the marinated chicken and sear all over for 8 to 10 minutes, turning regularly. Transfer to a roasting tray, then pop in the hot oven for 45 minutes, or until cooked through.
Meanwhile, cut the sweet potatoes into rough 2cm wedges. Toss with the paprika, semolina, a small pinch of salt and black pepper and a lug of olive oil.
Spread the wedges out on 2 large baking trays, then place in the oven for 25 to 30 minutes, or until tender and crisp.
To make the jalapeño salsa, drain and add the jalapeños to a food processor with a splash of the pickling juice. Tear in the coriander (stalks and all) and add a splash of extra virgin olive oil. Blitz well until smooth.
Serve the roast chicken with your piri piri sauce, sweet potato wedges and a little jalapeño salsa.