Whisk eggs and granulated sugar together in a bowl until frothy, about 3 minutes. Then, gently blend in the vegetable oil, milk, and vanilla extract until well combined.

Sift the plain flour and baking powder together over the wet mixture. Gradually fold in the dry ingredients until just combined, creating a smooth dough.

Divide the dough into two equal parts. Tint one half yellow and the other red using the food coloring, mixing until the colors are evenly distributed.

Preheat your oven to 350°F (180°C). Roll tablespoon-sized portions of the colored dough into balls and place them on a lined baking sheet.

Carefully place the cookie tray in the oven and bake for 12-15 minutes until the bottoms are golden brown and the tops remain soft and pale.

Once out of the oven, roll each cookie in granulated sugar while they're still warm for a sweet finish. Garnish with mint leaves if desired.