Whisk together the wine, thyme, oil, garlic, black pepper and parsley in a baking dish. Add the lamb and turn to coat. Cover and refrigerate for 30 minutes to marinate.
Remove the lamb from the marinade 20 minutes before cooking. Heat a grill pan or saute pan over high heat. Season the lamb with salt on both sides and cook until golden brown and seared on both sides and cooked to medium-rare doneness (internal temperature of 135 degrees F on an instant-read thermometer). Place on a cutting board and let rest for 5 minutes before slicing. Serve slices with a dollop of pesto on the side.
Piquillo Pepper Pesto:
Combine the peppers, pine nuts and garlic in a food processor and process until coarsely chopped. With the motor running, slowly add the oil and process until emulsified. Add the cheese, salt and pepper and pulse a few times to combine.