Heat the oven to 220C/Fan 200C/Gas 8.
In a large bowl combine the chicken pieces, kefir with the finely grated zest of the lemon and a peeled and grated garlic clove. Cover and set aside for a minimum of 30 mins, preferably overnight.
Peel and finely chop the shallots. Place a pan over a low heat and add 1 tbsp olive oil, the shallots and 1/2 tsp salt. Cover and cook for 10-15 mins until the shallots are soft and without colour.
Meanwhile peel, halve and core the pears and cut into 1cm dice. Turn the heat up to medium under the shallot pan. Add the sugar, vinegar, 2 tbsp water and the pear. Stir together, cover with the lid and allow to gently simmer for 20-25 mins until the sauce is viscous and the pear soft.
Quarter the potatoes into wedges. Place them into a pan, cover with cold water and add 1 tbsp salt. Bring the water to the boil, then reduce the heat to rolling boil and cook them for 5 mins. Drain them well and return the wedges to the pan with ½ tsp salt, cover and set over a low heat for 2-3 mins to steam. Shake the pan lightly to bash the edges of each wedge.
Pour 2 tbsp olive oil onto a roasting tin and place in the oven for 2 mins to get hot. Carefully and quickly add the potato wedges, coating each in the hot oil. Return the tray to the oven for 35-40 mins, turning the wedges over after 20 mins, so that they're cooked through and evenly crisp. In the last 5 mins of cooking, finely chop the rosemary leaves and scatter them over the potatoes.
Meanwhile, place the breadcrumbs on a tray. Season with salt and pepper. Drain the chicken pieces from the kefir and roll them in the crumbs so that each piece is evenly coated.
Heat 4 tbsp sunflower oil in a medium- large pan over a high heat. Once it begins to smoke remove the pan from the heat and reduce the heat to a medium flame.
Lower in half of the crumbed chicken, making sure not to overcrowd the pan as it will reduce the oil temperature and prevent each piece becoming crisp. Cook for 2-3 mins on each side or until crisp, evenly golden and cooked through. If you have a meat probe at home the core temperature should reach 65C.
Lift the chicken from the oil with a slotted spoon and set aside on a warm plate, lined with kitchen paper, while cooking the remainder. Serve hot, with the potato wedges, plenty of relish and a few lettuce leaves dressed with lemon juice, olive oil, salt and pepper.