For marinade combine soy sauce, vinegar and orange zest. Combine marinade and lamb racks and marinate at room temperature for 1-2 hours.
Preheat oven to 450F. Remove racks and pat dry and season with salt and pepper. Brown the racks on all sides in a large skillet, one at a time.
Move racks to large rimmed baking sheet. Cook for 15 minutes until med-rare. Cover with foil and let rest for 5 minutes before slicing.
In meantime emulsify cumin, coriander, lemon juice, garlic and olive oil. Toss with mint and arugula.
Spread greens on a serving platter. Top with sliced lamb almonds and mandarin slices.