Wash the legs and pat dry. Season with coarse salt and pepper. Place on a baking tray lined with baking paper and cook in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 45 minutes.
Meanwhile, for the aioli, peel the garlic and press it through a garlic press. Wash the chives and cut into small rolls. Mix egg yolk and mustard. Gradually add olive oil with the whisk of the hand mixer.
Season with salt, pepper and vinegar. Stir in garlic and chives. Wash, clean and slice the tomatoes. Melt butter in a pan. Fry the tomato slices for about 3 minutes while turning.
Season with salt and pepper. Arrange chicken legs and tomatoes in portions with chive aioli. Serve garnished with chives and lemon.