- 2 pounds fresh large poblano chiles
- 1 onion, quartered, cut crosswise into 1/4-inch slices
- 2 teaspoons dried oregano, preferably Mexican
- 3/4 cup crème fraîche or sour cream
- 1/4 cup shredded Monterey Jack
Preheat broiler, build a medium-hot fire in a charcoal grill, or heat a gas grill to high. If broiling, place chiles on a rimmed baking sheet. If grilling, put chiles directly on grill grate. Roast, turning occasionally, until tender and nicely charred all over, 15–20 minutes.
Transfer chiles to a large bowl; cover with plastic wrap and let steam for 15 minutes. Peel chiles. Halve lengthwise; discard seeds. Cut crosswise into 1/4-inch strips.
Heat a large dry heavy skillet over medium-high heat. Add onion; cook, stirring often, until beginning to char, 6–7 minutes. Add garlic; cook until fragrant, about 1 minute. Add oregano and 1 cup water; simmer until onion is tender and water has evaporated, 5–7 minutes.
Add chiles; cook until flavors meld, about 5 minutes. Remove from heat; stir in crème fraîche and cheese. Add water by table-spoonfuls if mixture is too dry. Season to taste with salt.