POBLANO POTATO GRATIN (for eight)
1-1/2 pounds fresh poblano chiles (about 5)
1 pound onions, cut lengthwise into ¼ inch strips
1 tablespoon vegetable oil
3 pounds large Yukon gold potatoes
1-1/2 cups heavy cream
¾ cup whole milk
1.Roast chiles and make rajas: Roast chiles on their sides on racks of gas burners, turning with tongs, until skins are blackened all over, about 10 minutes, or broil on a broiler pan 2 inches from heat, turning, 8 to 10 minutes. Immediately transfer to a bowl and let stand, covered tightly, 10 minutes.
2. When chiles are cool enough to handle, peel or rub off skin. Slit chiles lengthwise, then stem, seed and devein. Cut lengthwise into thin strips.
3. Cook onions with 1 teaspoon salt in oil in a 12 inch heavy skillet over medium low heat, stirring occasionally, until golden, about 8 minutes. Stir in chiles and remove rajas from heat. Reserve ½ cup rajas for topping.
4. Make gratin: Preheat oven to 400* with rack in middle. Generously butter a 3 quart shallow baking dish.
5. Peel potatoes, then cut crosswise into 1/16 inch slices (with an adjustable blade slicer). Transfer to a small, heavy pot. Add cream, milk and 1 teaspoon salt and bring just to a boil over medium heat, stirring occasionally (liquid will thicken). Stir in rajas, then pour mixture evenly into baking dish. Sprinkle reserved ½ cup rajas on top.
6. Bake until potatoes are tender, 45 minutes to 1 hour. Let stand 15 minutes before serving.
NOTE: Rajas can be made 3 days ahead and chilled. Gratin can be made 1 day ahead and chilled. Bring to room temperature and reheat, covered, in a 350* oven for about 30 minutes.
from Gourmet Special Edition: Gourmet Mexican cookbook