Wash potatoes thoroughly and cook in boiling salted water for about 20 minutes. In the meantime, clean and wash the fennel and cut it lengthwise into thin slices of approx. 1⁄2 cm. Clean and peel the carrots and cut them lengthwise into halves or quarters. Mix vegetables with 2 tbsp. oil, some salt and pepper. Distribute in a casserole dish.
Cut mozzarella into 8 thin slices. Remove chicken fillets with skin from the bone, wash and pat dry. Cut one pocket in each and season with salt and pepper. First spread the fillet pockets with pesto, then cover with mozzarella. Close the fillet pockets and tie them up with kitchen string. Place them with the skin facing upwards on half of a slightly oiled tray.
Preheat oven (electric cooker: 220 °C/circulating air: 200 °C/gas: see manufacturer). Drain the potatoes, allow to drain and spread on the other half of the baking tray. Press each half slightly flat with a potato masher. Drain the tomatoes (collecting the tomato oil) and cut into strips. Peel garlic and chop finely. Mix with 2 tablespoons of tomato oil and drizzle over the potatoes. Sprinkle tomatoes over them.
Place the casserole dish with the vegetables on a grid and the chicken/potato tray in the hot oven and bake for approx. 30 minutes (if the top and bottom heat is on, replace the tray and grid after approx. 15 minutes, cooking time may be extended by 5-10 minutes). Remove kitchen string from the meat, arrange with vegetables and potatoes.
Puree 30 g roasted pine nuts, approx. 50 g washed herbs (e.g. basil and some thyme), 50 g freshly grated Parmesan cheese and approx. 100 ml good olive oil with a hand blender. Season to taste with salt and pepper.
If there are still remains in the pesto glass, Sönke pours good olive oil on it - so it keeps cool for about 2 weeks
Colorful carrots: Not only look great, but also have different taste nuances: The purple ones taste especially sweet and juicy (watch out, they color), the yellow ones are a little bit harsher - therefore typical for e.g. stews.