Instructions

for the crust

Whisk sour cream and egg together in small bowl. Process flour, sugar, salt, and turmeric in food processor until combined, about 3 seconds. Scatter butter over top and pulse until butter is no larger than size of peas, about 10 pulses. Add half of sour cream mixture and pulse until combined, about 5 pulses. Add remaining sour cream mixture and pulse until dough begins to form, about 15 pulses.
Turn out dough onto sheet of plastic wrap and shape into 6-inch square, smoothing any cracks. Wrap tightly in plastic and refrigerate for 1 hour. (Dough can be refrigerated for up to 2 days.)

for the filling

Combine 1 tablespoon water, salt, and baking soda in large bowl. Add beef and mix until thoroughly combined. Let sit at room temperature for 10 minutes.
Heat oil in 12-inch nonstick skillet over medium-high heat until just smoking. Add beef mixture and cook, breaking up meat with wooden spoon, until beginning to brown, 5 to 7 minutes. Add scallions, garlic, habanero, thyme, curry powder, allspice, and pepper and cook, stirring frequently, until scallions are softened, about 3 minutes.
Add bread and remaining 1 cup water and stir to incorporate. Bring to boil, then reduce heat to low and simmer, stirring occasionally, until sauce thickens and coats beef, 8 to 10 minutes. Off heat, mash beef mixture with potato masher until fine-textured and bread is fully incorporated, about 2 minutes. Transfer to clean bowl and let cool completely. (Filling can be covered with plastic and refrigerated for up to 24 hours.)
Adjust oven rack to upper-middle position and heat oven to 375 degrees. Line rimmed baking sheet with parchment paper. Remove dough from refrigerator and cut into 4 equal pieces (about 7½ ounces each); cover with plastic. Working with 1 piece at a time, sprinkle dough with flour and roll into rough 11 by 9-inch rectangle (about ⅛ inch thick) on lightly floured counter, with long side parallel to counter edge, reflouring counter and dough as needed.
Place 2 scant ⅓-cup mounds of filling on bottom half of dough, about 4 inches apart and about 2 inches from bottom edge of dough. Flatten mounds to roughly 3-inch rounds. Lightly brush bottom half of dough with water. Fold top half of dough over filling, pressing along sides, bottom edge, and between filling to adhere.
Cut between mounds and trim edges to form two 5 by 4-inch rectangles. Crimp edges with floured tines of fork to seal, then transfer patties to prepared sheet.
Bake until patties have puffed and exteriors have lightly browned, about 30 minutes. Transfer patties to wire rack and let cool for 10 minutes before serving.

to make ahead

At end of step 8, transfer patties on baking sheet to freezer. Once frozen solid, patties can be transferred to zipper-lock bag and frozen for up to 1 month. To cook from frozen, extend baking time to 40 to 45 minutes, until bottoms are crisp.