This is the way I like to make my pie crust but feel free to make it the way you feel comfortable. Use a cheese grater to shred the butter into smaller pieces and place back in the fridge to keep cool. Meanwhile, mix tougher flour, almond flour, sugar and salt. Toss butter pieces into flour, coating the cold butter in flour. Then, use your hands to break up the butter a little more, but not too much so you don't warm it up. Add in the water 2 tablespoons at a time until the dough sticks together. You may only need to add 1/4 cup. Form a ball or disk with the dough and wrap in plastic wrap then, place back into the fridge to rest.
for the filling
Combine the sliced strawberries and rhubarb in a bowl with the sugar to let macerate at room temp for 10-20 minutes. While they are sitting and getting juicy, roll out the almond paste on a plastic cutting board or parchment paper into a 10 inch circle. This can sit at room temperature.
Preheat oven to 375 degrees.
Prepare the egg wash - 1 egg with a tablespoon of water and place the sliced almonds in a small bowl. Roll out the pie dough into a circle using more flour as needed. I like to turn and flip the dough as I'm rolling it to prevent it from sticking. Work quickly so the dough doesn't get warm!
Place rolled out pie dough on a ungreased baking dish. Layer the almond paste circle ontop of the dough in the center then spoon out the fruit (leaving behind any liquid) on top of that. Fold over the dough edges then brush with egg wash and sprinkle with sliced almonds.
Quickly place the galette into the oven and bake for 45-50 minutes, turning as needed to evenly brown the crust.
Remove from oven and let cool for 5 minutes. Galettes are best served the day they are cooked but also make a good breakfast the following day! Serve with vanilla ice cream or greek yogurt.
This can be made without the almond paste but I highly recommend it! Find it in most grocery store baking isles.