In a heavy-bottomed 2-quart saucepan, combine the white sugar, corn syrup, hot water, and salt over medium-low heat. Stir until the sugar dissolves completely.

Clip a candy thermometer to the saucepan. Without stirring, let the mixture come to a boil and reach 250°F (120°C), or until a drop in cold water forms a firm ball.

As the syrup heats, frequently brush down any sugar crystals from the pan sides with a wet pastry brush to prevent crystallization.

While the syrup is cooking, beat the egg whites in a chilled, clean bowl until they hold stiff peaks.

Once the syrup hits the right temperature, carefully remove the pan from the heat. Slowly pour the hot syrup into the whipped egg whites, beating continuously until the mixture thickens.

Stir in the vanilla extract and pecans (if using) until evenly distributed.

Using two spoons or a small cookie scoop, drop dollops of divinity onto a parchment-lined baking sheet.

Let the candies set at room temperature for at least 8 hours before storing in an airtight container.