1. Preheat the oven to 200°F and line two baking sheets with parchment paper.

2. Wipe the mixing bowl and whisk with vinegar or lemon juice, then dry well to remove any grease.

3. Add egg whites, cream of tartar, and salt to the bowl. Beat on medium speed until foamy and soft peaks form.

4. Add sugar one tablespoon at a time while beating on medium-high speed. Continue whipping until glossy stiff peaks form and the mixture feels mostly smooth.

5. Beat in vanilla extract and peppermint extract just until combined.

6. Paint thin red and green gel food coloring lines inside a piping bag fitted with a star or round tip.

7. Spoon the meringue into the piping bag and pipe small kisses or swirls onto the prepared baking sheets.

8. Add sprinkles or sanding sugar if using.

9. Bake for 1 hour and 15 minutes, or until the meringues are dry and lift easily from the parchment.

10. Turn off the oven and let the meringues cool inside with the door slightly cracked for 1 hour.

11. Store completely cooled meringues in an airtight container at room temperature.