Preparation Steps

• Assemble all the tools and ingredients.
• Preheat the oven to 350°F (180°C.)
• Peel and dice the onion.
• Chop the tomatoes and the roasted red bell peppers.
• Finely slice the garlic and finely chop the rosemary.
• Slice the potatoes, zucchini, and eggplant very thinly.

Cooking Steps

For the tomato sauce

• Warm the olive oil in a saucepan over medium heat, and add the onions, garlic, and rosemary with a pinch of salt. Fry for about 5 minutes, until softened but not colored.
• Add the tomatoes and the roasted peppers. Bring to a boil, then turn down to a simmer.
• Cook for about 30 minutes, stirring occasionally, until thickened and somewhat reduced. Season to taste with salt and black pepper, and (optional) blend with an immersion blender if you want a smooth sauce.

For the ratatouille

• Put the sliced vegetables into a large bowl with the olive oil, rosemary, and sliced garlic, season with salt and pepper, and toss to coat well.
• Add the prepared tomato sauce to a baking tray or ovenproof dish and spread it out over the base.
• Stack the sliced veggies upright in the baking tray, pushing them half into the tomato sauce. Try to more-or-less alternate potato, zucchini, eggplant, but don’t worry about getting it perfect.
• Continue until you have used all the vegetables; you may need to add a second layer, depending on how big your baking tray is.
• Cover the ratatouille with a lid or aluminum foil and bake for about 20 minutes.
• Uncover, and bake for 30 minutes more, until bubbling at the edges and the vegetables are slightly browned and crispy at the top.
• Leave to cool slightly for about 5-10 minutes before serving.