Caramel Corn Clusters

2 tablespoons vegetable oil
1/3 cup popcorn kernels
1 stick (1/2 cup) unsalted butter
1 1/2 cups packed light brown sugar
1/2 cup light corn syrup
3/4 teaspoon salt
1/2 teaspoon baking soda
1 cup (5 ounces) salted peanuts
Special equipment: a candy thermometer

Heat oil with 3 kernels in a 3-quart heavy saucepan, covered, over moderate heat until 1 or 2 kernels pop. Remove lid and quickly add remaining kernels, then cook, covered, shaking pan frequently, until kernels stop popping, about 3 minutes. Remove from heat and uncover.

Line bottom of a large shallow baking pan with foil. Lightly oil foil.

Melt butter in a 6-quart heavy pot over moderate heat. Add brown sugar and corn syrup and bring to a boil over moderate heat, stirring, then boil, without stirring, until syrup registers 300 degrees F on thermometer, 8 to 10 minutes. Remove pot from heat.

Using a wooden spoon or a heatproof spatula, stir salt and baking soda into syrup, then quickly stir in peanuts and popcorn to coat. Immediately spread
mixture in baking pan as thinly and evenly as possible. Cool completely, then break into bite-size pieces.

Makes about 12 cups.