I weigh out for all three batches of cookie dough at the same time into three different bowls. Weigh or measure the flour, salt, and baking powder into a bowl and run a whisk through to blend then set it aside. In a stand or handheld mixer, add the soft butter and beat till light and fluffy. Add the vanilla bean paste and the lemon juice and incorporate it. Turn the mixer down and add the powdered sugar and mix it into the butter. Next, if this is one of the two cookie dough that gets orange or green, add the color now. I only needed one drop, but if you like a deeper color, add two drops.
After mixing all three cookie doughs, I split each color in half and roll each one into a log shape. Lay each color next to each other on a piece of plastic wrap. Fold the one side of the plastic wrap over and lift the one side so you can flip it over to finish wrapping it around all three logs. I put the wrapped cookie dough into a 9X13 dish, and at this point, you can shape it into as close of a rectangular as you can. This way, when you slice the log, it will have even green, white (regular cookie dough color) and orange colors. Do the same for the other half of the dough. Put it in the refrigerator for at least an hour.
Preheat oven to 350° and line 2 cookie pans with parchment paper then set aside. Take one of the logs out of the refrigerator and slice ¼" pieces and lay flat on the cookie sheet. I put 15 to a cookie pan—Bake at 350° for 12-15 minutes. After baking, I let them cool on the pan for about a minute before moving them to a cooling rack.
I made three batches of cookie dough so I could get the green and orange color blended through each part of the cookie that needed color. The recipe makes ⅓ of the dough. You can take the recipe and times it by 3, then divide and add your colors to the two sections for the green and orange afterward, but I can never get equal parts that way. Whichever is more comfortable for you.Yields 30 flag cookies if you make three batches of dough.