Why This Recipe Works

Nutty romesco sauce unites roasted cauliflower and chickpeas with crisp, slightly bitter endive and tangy, quick-pickled red onion for a sheet-pan meal that’s a study in contrasts. High-heat roasting yields soft, burnished cauliflower and crispy chickpeas. Other bitter greens, such as escarole, frisée, and chicory, can be used in place of the endive.

Before You Begin

The sumac-pickled onion and the romesco sauce can be refrigerated separately for up to 3 days; bring them to room temperature before serving. The sumac adds tartness and fruitiness, but you can omit it. Use red wine vinegar if you don’t have sherry vinegar.

Instructions

Adjust oven rack to middle position and heat oven to 475 degrees. Combine 1 red onion, halved and cut through root end into ¼‐inch-thick slices; 2 tablespoons sherry vinegar; 2 tablespoons lemon juice; 1 tablespoon extra-virgin olive oil; 1 tablespoon ground sumac; ¼ teaspoon table salt; and ½ teaspoon sugar in bowl and microwave until steaming, about 2 minutes; set aside for serving.

Toss 1 head of cauliflower, cored and cut into 2‐inch florets; 1 rinsed can chickpeas; ¼ cup extra-virgin olive oil; and 1 teaspoon salt together on rimmed baking sheet, then spread into even layer over sheet. Roast until cauliflower is golden in spots, about 20 minutes. Stir, then redistribute evenly over sheet. Continue to roast until lightly charred throughout, 8 to 10 minutes.

Meanwhile, process ⅔ cup drained jarred roasted red peppers, ¼ cup toasted slivered almonds, ¼ cup fresh parsley leaves, 1 minced garlic clove, remaining 1 tablespoon sherry vinegar, remaining 3 tablespoons extra-virgin olive oil, and remaining ¼ teaspoon salt in food processor until smooth, about 1 minute. Season romesco with salt and pepper to taste.

Arrange 8 ounces Belgian endive leaves in even layer over serving platter, then top with cauliflower and chickpeas. Dollop with romesco, sprinkle with sumac onions and remaining 2 tablespoons fresh parsley leaves, and serve.