Creating Strawberry Macarons can be a rewarding experience. Follow these steps closely:

1. Prepare Baking Sheets: Line two baking sheets with parchment paper. If desired, use a template to ensure uniform shapes.

2. Sift Dry Ingredients: In a bowl, sift together the almond flour and powdered sugar to remove any lumps.

3. Whip Egg Whites: In a clean, dry bowl, whip the aged egg whites until foamy. Gradually add granulated sugar and continue whisking until stiff peaks form.

4. Add Flavoring: Mix in vanilla extract and a pinch of salt. If desired, add a few drops of red food coloring to achieve the right shade.

5. Fold Dry Ingredients: Gently fold the sifted almond flour and powdered sugar mixture into the whipped egg whites. Use a spatula to combine; be careful not to overmix.

6. Pipe the Mixture: Transfer the mixture into a piping bag fitted with a round tip. Pipe small circles onto the prepared baking sheets, leaving space between each round.

7. Rest the Macarons: Allow the piped macarons to sit at room temperature for 30-60 minutes until they form a skin and are no longer sticky to the touch.

8. Preheat Oven: Preheat your oven to 325°F (160°C).

9. Bake: Bake the macarons for 15-20 minutes. They should easily lift from the parchment paper without sticking.

10. Cool: Remove from the oven and let the macarons cool completely on the baking sheet.

11. Prepare Filling: In a mixing bowl, beat the softened butter until creamy. Gradually add the strawberry puree and lemon juice, mixing until smooth and well-combined.

12. Assemble Macarons: Pair macaron shells of similar sizes. Pipe the strawberry filling onto the flat side of one shell and sandwich it with the other shell.

13. Rest Again: Let the assembled macarons sit for at least an hour to allow the flavors to meld.