Rajas con Crema

Rajas con Crema (Poblano Strips with Onions and Cream)

2 pounds fresh poblano chiles (about 8)
1 medium white onion (about 8 ounces)
3 tablespoons vegetable oil
1/3 cup heavy cream

Roast and peel chiles. Cut chilies into 1/3-inch-thick strips. Halve onion lengthwise and cut each half lengthwise into 1/4-inch-thick slices. In a heavy skillet cook onion in oil over moderately low heat, stirring frequently, until softened, about 5 minutes. Add chilies and salt to taste and cook, stirring, 5 minutes. Add cream and cook, stirring, 2 minutes. Rajas may be made 1 day ahead and chilled, covered. Reheat rajas before serving.