Wash the thyme and chop it coarsely. Wash potatoes, dab dry, cut into slices. Distribute on a baking tray lined with baking paper. Sprinkle with 4 tablespoons of oil. Season with salt and pepper.
Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes. Turn the potato wedges after 15 minutes, sprinkle with 2 tablespoons of oil, season with thyme. Peel garlic and press it through a garlic press.
Mix mayonnaise and mustard, season with salt, pepper and garlic.