Preheat your oven to 250° and line baking sheets with parchment paper.
Clean the bowl of your mixer with a paper towel and white vinegar, to ensure there is no oil residue.
In the bowl of a stand mixer fitted with the whisk attachment, add egg whites, cream of tartar, and salt. Beat on medium-high speed until egg whites have foamed up.
Turn the speed down to medium-low and slowly and steadily pour in the sugar in a slow stream. Don't dump it all in, it may clump. Turn speed back up to medium-high for 8 to 10 minutes until stiff, glossy peaks form.
Add lemon, vanilla extract and food coloring. Mix until combined.
Place the meringue mixture into a piping bag fitted with a star piping tip.
Place dollops onto the parchment-lined baking sheet. No need to leave a ton of room between cookies, they don't spread.
Bake for 50 minutes, then turn off the oven without opening the door.
Leave the meringue cookies in the oven for 1 hour. Then remove from the oven, cool completely, and store in an airtight container at room temperature.