Step 1: Prepare the Crust

1. Preheat the Oven – Set your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper or lightly grease it with nonstick spray. This will help you remove the bars easily once they’re baked.
2. Mix Dry Ingredients – In a mixing bowl, sift together 2 ½ cups of flour, powdered sugar, and salt. Sifting ensures a smooth crust without lumps.
3. Add Butter – Pour in the melted butter and mix until combined. The dough should be slightly crumbly but hold together when pressed.
4. Press Into Pan – Transfer the crust mixture to the prepared baking dish and press it down into an even layer. Using the bottom of a measuring cup helps achieve a smooth surface.
5. Bake the Crust – Bake for 20 minutes or until the edges turn a light golden color. Remove from the oven and set aside while preparing the filling.

Step 2: Prepare the Lime Filling

1. Mix Sugar and Lime Zest – In a food processor or mixing bowl, blend granulated sugar and lime zest. This step enhances the citrus flavor by infusing the sugar with the zest’s natural oils.
2. Incorporate Dry Ingredients – Add the remaining ½ cup of flour to the sugar mixture and mix well.
3. Add Wet Ingredients – Pour in the lime juice, eggs, and food coloring (if using). Whisk or blend until completely smooth and combined. The food coloring is optional but enhances the lime appearance.
4. Pour Over Crust – Slowly pour the lime mixture over the pre-baked crust, ensuring an even spread.

Step 3: Bake and Chill

1. Bake for 30-40 Minutes – Place the pan back in the oven and bake until the center is set. Check after 15 minutes and rotate the pan for even baking.
2. Check for Doneness – Lightly jiggle the pan; if the center doesn’t wobble, the bars are ready. Avoid overbaking, as this can cause cracks.
3. Cool Completely – Let the lime bars cool at room temperature for an hour before transferring them to the refrigerator.
4. Chill for At Least 2 Hours – Chilling is crucial for the bars to firm up and develop the best texture.

Step 4: Finishing Touches

1. Dust with Powdered Sugar – Once fully chilled, sprinkle a light layer of powdered sugar over the top for a classic look.
2. Cut into Squares – Using a sharp knife, cut into 16 even bars. For cleaner slices, wipe the knife with a damp cloth between cuts.