Remove the skin from the chicken legs. Cut the legs in the joint, wash the upper and lower legs, dab dry, sprinkle with lemon. Cover and marinate in the refrigerator for about 30 minutes.
Soak chillies in hot water for about 10 minutes. Peel shallot and garlic and dice finely. Peel ginger and grate finely. Dab chillies dry and chop them. Mix the shallot, garlic, ginger, coriander seeds, garam masala, chilli powder and 1 teaspoon salt in a mortar to a smooth paste.
Mix with yoghurt and colour it red with a few drops of food colouring.
Place chicken legs in a large flat dish and spread yoghurt sauce all around. Spread the rest of the sauce over it. Cover and leave in the refrigerator for at least 4 hours, preferably overnight.
Preheat oven (electric cooker: 200°C/circulating air: 175°C/gas: level 3). Put the legs on the rack, slide them over the fat pan into the hot oven, bake for approx. 40 minutes. Then under the oven grill or at the highest temperature (electric oven: 250°C/circulating air: 225°C/gas: level 5).
Grill for 8-10 minutes. Arrange legs and garnish. Serve with papadams.