Preheat the oven to 200 degrees. Peel the three carrots and two parsnips and cut them into large chunks. Peel the red onion and cut it into wedges. Mince the garlic and combine it in a bowl with a splash of olive oil and a generous amount of cumin. Rub the four lamb chops with this marinade and let the meat rest on the counter so the flavors can infuse.
Spread the cut carrots, parsnips and red onion evenly on a baking sheet. Drizzle the vegetables with a little olive oil and roast them in the oven for 25 minutes until tender. Toward the end of the roasting time, heat a grill pan over high heat. Grill the marinated lamb chops in the dry, hot pan for exactly 3 minutes per side.
Meanwhile, chop the fresh mint as finely as possible. Put the 150 grams of Greek yogurt in a small bowl and stir in the finely chopped mint until smooth.
Remove the baking sheet from the oven and divide the warm roasted root vegetables directly onto plates. Place a freshly grilled lamb chop on each portion of vegetables and serve with a generous dollop of the mint yogurt.