Heat oven to 180C/fan 160C/gas 4. Put the almonds and garlic in a food processor and process to a rough paste. Brush the fat side of the racks with a little mustard, then press the almond crust onto it. Roast for 30-40 mins until the lamb is browned on the outside and pink inside. Leave to cool, then wrap in foil and chill for up to 24 hrs.
Put all the herb relish ingredients in the food processor and process to a rough paste. Pour into a small bowl. When ready to serve, cut the lamb between the bones into little cutlets and arrange over a platter. Spoon a little herb relish onto each or serve separately in a small bowl.