Peel and finely chop the onion. Peel and crush or finely chop the garlic cloves. Pick the rosemary leaves and finely chop them. Pour 1 tbsp oil into a pan and bring to a medium heat.
Slide the onions and garlic into the pan. Sprinkle in 1 tsp dried oregano, the chopped rosemary and a pinch of salt and pepper. Fry for 5 mins, stirring occasionally, till softened.
Pour the tinned cherry tomatoes into the pan. Bring to the boil, then reduce the heat to a gentle simmer and cook for 10 mins.
Meanwhile, make the carrot ribbon salad. Trim and peel the carrots, then use a vegetable peeler to create ribbons. When you get to the middles, thinly chop the remaining carrot. Slide into a bowl. Squeeze the lemon juice into a separate small bowl, and whisk in 1 tbsp oil and a little salt and pepper to form a dressing.
Preheat your grill to medium-high. Stir the gnocchi into the tomato sauce till evenly coated, then pour everything into an ovenproof dish. Tear the mozzarella into rough chunks and dot on top. Grind over a little black pepper and slide under the grill. Cook for 5 mins, till the cheese is golden and the sauce is bubbling.
Toss the carrot ribbons with the lemon dressing and serve with the golden grilled gnocchi.