Sea Foam Candy

Make about 3 dozen 2-inch candies

You'll need two pieces of equipment to make this confection: a standing mixer and an instant-read thermometer that can read high temperatures. (A candy thermometer is ideal; see related testing.) These candies must be prepared on a dry day or in a dry, cool environment; they will not set up properly in hot or humid conditions.

1. Adjust oven rack to middle position; heat oven to 350 degrees. Spread nuts in single layer on rimmed baking sheet. Toast nuts until fragrant and lightly browned, 10 to 12 minutes, stirring once or twice. Cool nuts to room temperature. Select 40 pecan halves for garnish and set aside; coarsely chop remaining nuts. Place chopped nuts in mesh strainer and shake to remove dust; set chopped nuts aside. Line 2 baking sheets with waxed or parchment paper; set aside.

2. Pour water into 2- to 3-quart heavy-bottomed saucepan; add sugars and corn syrup to center of saucepan, taking care to keep sugar granules from coating sides of pot. Bring to boil over high heat without stirring; reduce heat to medium and cook, without stirring, until syrup registers 255 degrees on instant-read or candy thermometer, about 14 minutes.

3. After reducing heat under sugar syrup, fit standing mixer with whisk attachment and beat egg whites at high speed until mixture forms stiff peaks when whisk is lifted, about 60 seconds; turn off mixer. When sugar syrup is ready and with mixer set at medium speed, pour syrup in slow, steady stream into egg whites; add salt. Increase speed to high and continue beating until mixture loses its sheen and holds medium-stiff peaks when whisk is lifted, 15 to 25 minutes. (Begin checking as soon as thin threads of mixture start to pull away from sides of bowl; see "When Is It Done?" below.) Add vanilla, vinegar, and chopped nuts; beat on medium speed until just combined, about 10 seconds.

4. Working quickly, drop rounded tablespoons of mixture (or use 1 3/4-inch spring-loaded ice cream scoop) onto prepared baking sheets. Garnish each round with pecan half, pressing gently to adhere. Let stand at room temperature until firm, 2 to 4 hours. Peel candies off paper and transfer to airtight container, sliding fresh sheets of waxed or parchment paper between layers of candies. Sea foam will keep for up to 1 week.