Recipe adapted from Bon Appetit
120g (1 cup) all-purpose flour
40g (1/3 cup) buckwheat flour
113g (1 stick) butter, cold
40ml (2 Tbsp) ice water
2 Tbsp sugar
pinch of salt
500g rhubarb stalks
100g castor sugar
1.5 Tbsp cornstarch
Egg wash (1 small egg whisked with a splash of water)
Optional – Rhubarb Glaze:
150g (5ox) tops and tails of rhubarb
100g (1/2 cup) castor sugar
A splash of water
1. Whisk all-purpose and buckwheat flours, sugar, and salt in a large bowl to combine. Add butter and work into dry ingredients with your hands, mashing it into big flat pieces and smooshing it between your palms into the flour, until you have pea- and nickel-size pieces.
2. Drizzle ¼ cup ice water over mixture and rake it in with your fingers until evenly dispersed. Squeeze clumps with your hands to moisten until a shaggy dough forms, then turn out onto a work surface.
3. Gather dough together, pushing and working it into a ball, then flattening it, until only a few dry spots remain. Pat into a ¾”-thick square. Using a bench scraper or knife, divide dough into 4 pieces. Stack pieces on top of one another, placing any unincorporated dry bits in between layers, and press down to combine. Form dough into a ¾”-thick disk and wrap tightly in plastic. Chill until firm, at least 2 hours and up to 3 days.
Filling and Assembly
5. Roll out dough on a well-floured surface to a 14″ round, rotating dough and tossing more flour underneath as needed to keep it from sticking. Transfer dough to the baking sheet and refrigerate to chill.
6. Prepare the rhubarb: cut off and discard the leaves, trim off and reserve the ends of each stalk. Cut the stalks into three or four pieces and then cut each piece lengthwise into 5mm (1/4″) strips. Toss the rhubarb pieces with the cornstarch and sugar in a medium bowl.
7. Remove the baking sheet from the fridge and arrange and mound the rhubarb filling in center of dough, making sure to leave a 4cm (2″) border around edges. Fold dough up and over filling, overlapping slightly, and make a decorative edge. Brush dough with egg wash and sprinkle dough and filling generously with turbinado sugar for a nice crunch.
8. Bake galette until filling is bubbling and crust is deeply browned, 40–50 minutes. Let cool slightly and serve with whipped cream.
You can make a glaze for the galette by boiling the reserved bits or rhubarb with the sugar and water until the fruit is soft. Strain the syrup into a bowl and brush it over the baked galette for a nice shine.