Step 1 Preheat oven to 200ºC.Spray a large frying pan with oil and place over high heat. Add lamb and sear for 2 minutes each side, until brown all over. Transfer to a baking tray and roast for 6–8 minutes (depending on thickness). Remove from oven, cover loosely with foil and rest for 5 minutes.
Step 2 Place tomatoes cut side up on a baking tray lined with baking paper. Drizzle with balsamic, season with pepper and roast for 10 minutes, or until wilted. Transfer to a bowl and add half the mint.
Step 3 Meanwhile, cook peas in a large saucepan of boiling water for 2–3 minutes, or until bright green and tender. Drain well. Place peas into a food processor with olive oil, lemon, garlic and mint. Process, leaving some texture.
Step 4 Slice lamb into 1cm thick slices. Divide lamb, mash and tomatoes between serving plates. Drizzle with extra balsamic. Serve with spinach and bread rolls.