Created by ImPat on June 24, 2020
Step 1: To make marinade, combine all ingredients in a jug and pour half into a large bowl and refrigerate remaining marinade.
Step 2: Add lamb to marinade in bowl and turn to coat and refrigerate, covered, for 2 hours.
Step 3: Cut potatoes in half lengthways and toss in oil and season and then arrange, cut-side up, in a single layer in a large roasting pan.
Step 4: Cook in a hot oven (200C) for about 45 minutes, or until tender and then remove.
Step 5: Meanwhile, remove lamb from marinade and pat dry with absorbent kitchen paper and discard marinade in bowl.
Step 6: Heat an oiled, large barbecue grill plate over a medium heat and add lamb and cook for about 4 minutes on each side, or until tender and then remove and rest, loosely covered with foil for 5 minutes.
Step 7: Place reserved marinade in a small saucepan and bring to a boil and gently boil, stirring occasionally for about 5 minutes, or until thickened and remove.
Step 8: Drizzle sauce over lamb and serve with potatoes topped with sour cream and chillies (optional).