Thinly slice the red onion. Heat a tablespoon of olive oil in a skillet over a medium/high heat. Add the ground lamb. Add the sliced onion to the skillet along with a generous pinch of salt and pepper. Stir well to combine. Pan fry the lamb and onion, breaking the lamb into small pieces as you cook. Pan fry until the lamb is browned all over, completely cooked through and the onion is soft. About 8-9 minutes.
Whilst the lamb is cooking you can prepare the dressing. Very finely crush the garlic and add to a small mixing bowl. Add a generous teaspoon of tahini. Add the lime juice, remaining olive oil and a pinch of salt. Whisk together until smooth and well combined.
Clean the lettuce leaves and trim any tough stalks. Arrange the leaves on a large serving platter or individual plates. Divide the cooked lamb and onion evenly between the four prepared lettuce cups, filling the center of each.
Drizzle the tahini dressing evenly over each lamb filled lettuce cup. Finely chop the cilantro. Scatter the cilantro over the lettuce cups. Serve the lamb hot with your preferred Keto sides.