Mix the oil, the juice of half the lemon, and the Dijon mustard to a marinade. Wash the thyme, pick the leaves, and add them together with 1 garlic clove (finely sliced) to the marinade. Season with salt and pepper. Preheat the oven to 200C.
Cut the potatoes into four parts each, peel the onions and cut into parts. Cut the remaining half of the lemon into thin slices. Add the potatoes, onions and lemon slices to the marinade and mix thoroughly. Leave to soak.
Wash the chicken thighs and dab dry. Cut the remaining garlic clove into fine slices and place them under the chicken skin.
Dab the chicken thighs with olive oil, and season with salt and pepper. Place on a tin and bake for 15 minutes (at 200C), until the skin starts to get crispy.
Add the potatoes, onions, and lemon slices to the chicken and bake for another 35 minutes.
