Preheat oven to 180 degrees Celsius (355F). Then make your dough by mixing in a bowl the flour, cold water and olive oil until it forms the dough.
Between 2 sheets of baking paper, roll the dough in a large flat circle shape using a rolling pin and place on an oven tray.
Slice the nectarines and mix them with the flour and sugar then assemble your galette by spreading the nectarines in the middle of your crust in circles.
Fold the edges in a rustic manner overlapping and cook the galette in the oven for 35-45 minutes at 180 degrees Celsius (355F). Leave to cool then slice. Serve with dairy-free vanilla ice-cream or homemade cashew lemon sauce.