Tip the breadcrumbs into a dry frying pan. Stir and cook over a medium heat for 2-3 mins till the breadcrumbs are golden and toasted. Tip them into a food processor or blender.
Pick the leaves off the mint sprigs. Finely grate the zest from the lemon. Juice it. Peel and chop the garlic. Add them all to the processor. Add half the spinach. Season.
Turn the food processor on. Add 5 tbsp olive oil to the processor while it’s blitzing, till you have a thick, smooth pesto. If you think it’s too thick, add a little more oil. Taste and adjust the seasoning. Put to one side.
Fill the kettle and boil it. Scrub the potatoes. Roughly chop them. Trim and peel the carrots. Thickly slice them. Fill a pan with hot water from the kettle.
Add the potatoes to the hot water. Cover. Bring to the boil. Turn the heat down. Simmer for 10 mins. Add the carrots. Simmer for another 5 mins till the veg are tender.
While the veg cook, warm a griddle or frying pan. Brush the lamb with ½ tbsp olive oil each and season. Fry for 3-5 mins, depending on how pink you like lamb. Flip. Fry for another 3-5 mins. Pop on a plate. Cover with foil. Rest for 5-10 mins.
Drain the potatoes and carrots. Tip back into the pan. Add ½ tbsp olive oil and some seasoning. Toss to coat. Serve the veg with the lamb leg steaks and around 1 tbsp pesto on each.