In a medium bowl, whisk together the garlic, mint, lemon zest and juice, olive oil, 2 teaspoons of salt, and ½ teaspoon of pepper.
Place lamb in a large sealable bag and add marinade ingredients and refrigerate overnight.
Let lamb stand at room temperature for 1 hour.
Preheat the oven to 200°C / 400°F / Gas mark 6.
Remove lamb from marinade, brush off any garlic and mint, and pat dry with paper towels gently and discard the marinade.
Season the lamb with salt and pepper.
Heat the rapeseed oil in a large ovenproof skillet over medium-high heat.
Add lamb and flipping it once cook until browned, 2 to 3 minutes per side.
Transfer the skillet to oven and cook until lamb registers 130 degrees on an instant-read thermometer, 20 to 25 minutes for medium-rare.
Make the caper-mint sauce by using a food processor to pulse the capers food until roughly chopped.
Add the mint, lemon zest and juice, shallots, and pulse until the mint is roughly chopped.
Add the olive oil in a slow, steady stream, pulsing until combined but still coarse.
Transfer to a small bowl.
Transfer the lamb to platter and coat the racks with a third of the sauce.
Let rest for 20 minutes.
Cut the lamb into chops, single or double as preferred then transfer to a serving platter.
Garnish with lemon wedges and mint sprigs and serve with remaining sauce.