In a small bowl, stir strawberries, lemon juice and 1 tablespoon granulated sugar until combined. Let sit for 10 minutes, then drain.
In a medium bowl, whisk together flour, baking powder, and salt.
In a large bowl using a hand mixer, beat butter, remaining ½ cup sugar, and light brown sugar until light and fluffy. Beat in egg and vanilla extract, then stir in flour mixture until just combined(do not overmix, else the cookies will turn out hard).
Using a wooden spoon, very gently fold in strawberries.
Roll the dough into 2 logs, cover with cling film or plastic wrap tightly and refrigerate for 20 mins. Refrigerating the dough makes it easy to handle.
Take the dough out of the fridge, slice the logs into 1/4 inch thick circles, arrange them 2" apart and bake until cookies are set and just golden around edges, about 18 - 20 minutes.
Alternatively, you can use a medium cookie scoop, scoop heaping tablespoons of dough on to the parchment paper, flatten them and bake until cookies are set and just golden around edges, about 18 -20 minutes.
Take them out onto a wire rack, cool completely and store in an air-tight container.
Kids can enjoy dunking them in warm milk.