Instructions

• Preheat the oven to 400°F and set a large rimmed baking sheet on the middle rack.
• Arrange 1 ½ pounds poblano peppers, the 1 large sweet onion (peeled and cut into wedges), 1–2 jalapeños (optional), and 4–6 whole garlic cloves on the baking sheet. Drizzle with 1 tablespoon olive oil and toss or turn to coat.
• Roast in the oven for 15–20 minutes, until the pepper skins are blistered and the onion and garlic are softened.
• Remove the baking sheet and let the roasted vegetables cool until they are easy to handle.
• Peel the waxy skins off the poblano peppers. Remove the stems and shake out the seeds, leaving the soft pepper flesh. If you roasted jalapeños and want less heat, remove their stems and shake out the seeds as well.
• Peel the skins from the roasted garlic cloves and discard any loose burnt bits. (The roasted onion wedges do not need additional prep.)
• Place the roasted poblano flesh, roasted onion wedges, roasted garlic, and the jalapeños you want to include into a blender. Pour any pan juices from the baking sheet into the blender.
• Add ½ cup chopped cilantro, 2 teaspoons ground cumin, 1 ½ cups vegetable broth or water, ¼ cup fresh lime juice, and ½ teaspoon salt to the blender.
• Cover and purée until very smooth. Taste and add additional salt and pepper if needed.
• If you want more heat, add the remaining jalapeño(s) (up to the 1–2 total from the ingredient list) and purée again. Use the sauce immediately or store refrigerated.