1. In a small bowl, mix together 2 teaspoons of the baking soda with the citric acid and set it aside.
2. Attach a candy thermometer to a large saucepan, then mix the sugar, water, and corn syrup together and bring to a boil over medium heat, stirring frequently, about 7 minutes. If crystals form on the side of the pan, wipe them off with a brush dipped in cold water. When the mixture boils, stop stirring and let the temperature reach 305 degrees F, about 10 minutes more.Science Note:
3. The temperature is important as it determines the hardness of a candy.
4. Meanwhile, sift the confectioners sugar over a parchment paper lined cookie sheet and sprinkle half the citric acid mixture on top of that.
5. When the sugar mixture reaches 305 degrees F, turn off the heat (the temperature will rise a bit after this). Let the temperature drop to 275 degrees F, about 2 minutes, then stir in the flavoring and food coloring. Stir in the remaining baking soda. The mixture will immediately get foamy and thicken. Working quickly, pour it onto the cookie sheet. Sprinkle the remaining citric acid mixture on top of the candy.
6. Let the candy cool and harden, about 15 minutes. Break into large pieces. Put them in a doubled freezer bag and break them into crumbs with a hammer. Store in an airtight container.