Finely chop the onion, carrot and celery. Heat 1 tbs olive oil in a medium deep frypan over medium heat. Cook the onion, carrot and celery, stirring occasionally, for 10-12 mins until soft.
Step 2 — Prep ingredients
Meanwhile, bring a large saucepan of salted water to the boil for the ravioli. Lightly grease a 1.5L (6 cup) baking dish. Finely chop the garlic, then using the flat side of the knife, mash to a paste (see cooking tip). Finely chop the parsley, including the stems. Finely grate the zest of half the lemon*, then juice the half. Finely grate the parmesan.
Step 3 — Simmer sauce
Add the Italian seasoning and half the garlic to the vegetables and cook, stirring, for 30 secs or until fragrant. Stir in the tomatoes, half the tomato paste* and 125ml (½ cup) water. Bring to a simmer over medium-high heat and cook, stirring regularly, for 3-4 mins until slightly reduced.
Step 4 — Cook ravioli
While the sauce is simmering, preheat the grill to high. Cook the ravioli in the pan of boiling water for 3 mins or until al dente. (Handle the ravioli with care to ensure they don't break up or burst open.) Drain.
Step 5 — Assemble and grill
Stir 1 tsp sugar and 1 tsp balsamic vinegar into the sauce. Taste, then season with salt and pepper. Spread half the sauce over the base of the baking dish. Put the ravioli on top of the sauce, overlapping to fit. Spoon over the remaining sauce, then scatter with the parmesan. Grill for 5 mins or until the parmesan is melted and golden.
Step 6 — Make gremolata drizzle
Combine the parsley, lemon zest, remaining garlic, 2 tsp lemon juice* and 1 tbs extra virgin olive oil in a bowl and season with salt and pepper. Divide the ravioli among bowls, or take the bake straight to the table. Spoon over the gremolata drizzle to serve.