Set your oven broiler to high and position a rack about 4 inches from the heat source.

Whisk the lemon juice, minced garlic, and sour cream together in a small bowl until smooth, then gradually whisk in the olive oil until the dressing is emulsified.

Thread the lamb cubes onto skewers and arrange them on a broiler pan.

Broil the lamb for 4 minutes, then turn the skewers over and broil for another 4 minutes until the meat is browned and cooked through.

Place the cooked lamb in a shallow dish and drizzle with 3 tablespoons of the prepared dressing to coat the meat.

Combine the arugula and sliced red onion in a large bowl, toss with the remaining dressing, and divide between two plates.

Top the dressed greens with the warm lamb skewers and finish by sprinkling with the crumbled feta.