Bring a large saucepan of salted water to the boil for the ravioli (speed things up by using your kettle to boil the water). Thinly slice the onion and capsicum. Crush or finely chop the garlic.
Step 2 — Start sauce
Heat a generous drizzle of olive oil in a medium deep frypan over medium-high heat. Cook the onion and capsicum, stirring occasionally, for 4-5 mins until softened.
Step 3 — Add garlic and seasoning
Add the garlic and Italian seasoning to the capsicum mixture and cook, stirring, for 1 min or until fragrant.
Step 4 — Finish sauce
Stir the tomatoes, capers (you can omit the capers and serve them at the table, if you prefer) and ½ tsp sugar into the capsicum mixture and bring to a simmer. Reduce the heat to medium and cook, covered, stirring occasionally, for 2-3 mins to develop the flavour. Taste, then season with salt and pepper.
Step 5 — Cook ravioli
Meanwhile, cook the ravioli in the pan of boiling water for 3 mins or until al dente. Drain.
Step 6 — Get ready to serve
Add the ravioli and spinach to the sauce and gently toss to coat (handle the ravioli with care to ensure they don't break up or burst open). Divide the ravioli among bowls to serve.