8 side-dish servings.

Preheat oven to 325°

If using fresh poblanos, char chiles over gas flame or in broiler until blackened on all sides, turning occasionally. Wrap in plastic and cool 10 minutes. Peel, seed and chop chiles.

Bring water, butter and salt to boil in heavy medium saucepan. Add rice, return to boil, cover, reduce heat to low and simmer about 16 minutes. Transfer to large bowl and cool rice, stirring with a fork.

Butter 2-quart shallow baking dish. Heat oil in medium skillet over medium heat. Add onion and garlic, and saute until transluscent, about 3 minutes. Add chopped chiles and saute 1 additional minute. Add chile mixture and corn to rice in bowl. Add sour cream and cheese to rice and stir. Transfer mixture to prepared dish. (Can be made 1 day ahead. Cover and chill. Let stand 2 hours at room temperature before continuing.) Bake rice at 325° for about 25 minutes (until heated through and sides are light brown.)