½ red onion, thinly sliced
2 tablespoons vegetable oil
¾ teaspoon kosher salt
4 poblano peppers, cut in half lengthwise and seeded
⅓ cup heavy whipping cream or half-and-half
Juice of ½ lemon
1 tablespoon sour cream
1 teaspoon ground cumin
SET an oven rack 6 inches below the broiler. Preheat the broiler on high.
On a large rimmed sheet pan, toss the onion with 1 tablespoon of the oil and ¼ teaspoon of the salt. Scatter the onions around the pan.
Rub the peppers with the remaining 1 tablespoon oil and sprinkle with ¼ teaspoon of the salt. Arrange the peppers, cut sides down, on the onions. Broil until the tops of the peppers are blistered, about 8 to 10 minutes. Remove from the oven. Cover with foil or a clean cotton kitchen towel; let stand for 5 minutes.
Meanwhile, in a small bowl, stir together the whipping cream, lemon juice, sour cream, cumin, and remaining ¼ teaspoon salt; set aside.
Peel the peppers and slice into long strips. Transfer to a medium bowl and add the onion and cream mixture. Toss to combine.