- 3 large zucchini (about 1 1/2 pounds), 1 finely diced
- Kosher salt
- 1/4 cup extra-virgin olive oil
- 1/4 small onion, finely diced
- 1 garlic clove, minced
- 1 teaspoon tomato paste
- 1 medium red bell pepper, finely diced
- 1 medium yellow bell pepper, finely diced
- 1 large tomato—peeled, seeded and finely diced
- Piment d'Espelette (see Note)
- 1 tablespoon chopped mint
- 1 tablespoon chopped oregano
- 1 tablespoon chopped basil
- 2 ounces freshly grated Sbrinz cheese or Parmigiano-Reggiano (about 2/3 cup)
- Cut the 2 whole zucchini into twelve 1/2-inch-thick diagonal slices each and season with salt. Transfer to a rack and let stand for 30 minutes. Rinse and pat dry.
- Meanwhile, heat 2 tablespoons of the olive oil in a large skillet. Add the onion and garlic and cook over low heat, stirring, until softened, about 4 minutes. Add the tomato paste and cook, stirring, for 2 minutes. Add the red and yellow peppers along with the diced zucchini and cook, stirring occasionally, until softened but not browned, about 6 minutes. Add the diced tomato and cook, stirring occasionally, until softened, about 5 minutes. Season with salt and piment d'Espelette. Stir in the mint, oregano and basil.
- Preheat the oven to 400°. Heat the remaining 2 tablespoons of olive oil in a large skillet. Season the zucchini slices with salt and piment d'Espelette, add them to the skillet and cook over high heat, turning once, until browned in spots, about 4 minutes. Arrange the zucchini in a 9-by-13-inch baking dish in a single layer and spoon the pepper mixture on top. Sprinkle with the cheese and bake in the upper third of the oven for about 25 minutes, or until the cheese is melted and lightly browned. Serve hot or warm.
The gratin can be assembled up to 6 hours ahead. Keep at room temperature until ready to bake.
Piment d'Espelette is a spicy ground red pepper from the Basque region of France. It's available at specialty food stores.
Switzerland's principal white grape, Chasselas, produces full-bodied but very crisp white wines, ideal partners for vegetable dishes involving cheese, like Humm's zucchini gratin. if that's difficult to track down, substitute a good northern Italian Pinot Bianco.