1. Preheat the oven to 200°C (400°F)

2. Peel and thinly slice the onion. Spread across a large roasting pan. Drizzle with 60 ml (¼ cup) olive oil and season with salt and pepper. Roast for 20 to 25 minutes until golden and soft.

3. While the onion roasts, peel and thinly slice 3 garlic cloves. Remove the seeds from the chili pepper and slice finely. Place in a mixing bowl with the thyme sprigs.

4. After the onion is roasted, remove the pan from the oven. Add the garlic, chili, and thyme to the pan. Stir to combine.

5. Cut the tomatoes in half and add them to the roasting pan. Drizzle with the remaining 60 ml (¼ cup) olive oil. Season with salt and pepper. Toss gently to mix.

6. Return the pan to the oven. Roast for another 20 to 25 minutes until the tomatoes have broken down and the edges are lightly charred.

7. Remove from the oven and let rest for 5 minutes. Discard the thyme sprigs. Stir in the lemon zest.

8. Serve warm. Use as a pasta sauce, topping for grilled chicken, fish, or roasted vegetables, or as a savory spread. Stores well refrigerated for up to 5 days or frozen for 3 months.