Preheat the oven to 220C, fan-forced. Line 2 oven trays with baking paper. Using a sharp knife, cut slits 5mm apart across each potato, taking care not to cut all the way through (see Kitchen hack). Put the potatoes on a lined tray, drizzle with 2 tsp olive oil and season with salt and pepper. Roast for 20 mins.
Step 2 — Roast lamb
Meanwhile, combine 3 tsp pepper and garlic seasoning and 2 tsp olive oil in a large bowl and season with salt. Add lamb and turn to coat. Heat a medium frypan over high heat until hot. Cook lamb, turning regularly, for 4 mins or until browned. Transfer to remaining tray. Roast lamb for 10-13 mins for medium-rare, or until cooked to your liking. Remove from oven and rest for 8 mins.
Step 3 — Roast zucchini
When the potatoes have been roasting for 20 mins, quarter the zucchini lengthwise, then cut into 2cm chunks. Add the zucchini to the tray with the potatoes and season with salt and pepper. Roast for a further 15 mins or until the veggies are golden and tender.
Step 4 — Cook peas
While the veggies are roasting, bring a small saucepan of water to the boil. Add the peas and cook for 2 mins or until tender. Drain.
Step 5 — Serve up
Combine 2 tsp olive oil, 1 tsp white wine vinegar and any resting juices from the lamb in a bowl. Add the peas to the tray of roasted veggies, drizzle with half the dressing and toss to combine. Slice the lamb. Divide the lamb and veggies among plates. Crumble over the feta, drizzle with the remaining dressing and enjoy!
Step 6 — Kitchen hack
For easy breezy slicing, put a chopstick on either side of the potato, as this will prevent your knife cutting all the way through. Or, skip the hasselback slices and simply halve the potatoes before roasting instead.