In bowl of food processor, place flour, sugar and butter. Pulse minimally until butter is mostly incorporated and loose, crumbly powder forms.

Add 6 tablespoons water and pulse until clumps form. At this point, if clumps can be formed into dough by hand, move to step 3. If mixture is too crumbly to form into dough, add additional cold water 1 tablespoon at a time just until mixture can be hand-formed into dough.

Form dough into rectangular block, wrap in plastic wrap and refrigerate at least 1 hour.

Preheat oven to 350 degrees F. Line baking sheet with parchment paper or silicone mat.

Remove dough from fridge, unwrap and place on large, lightly floured surface or countertop. Using floured rolling pin, gently roll dough out to 1/8-inch thickness, or as thin as possible without breaking it, until 12-½ × 16 inches. (Note: If work surface is not large enough, split dough into two parts before rolling and refrigerate second part until ready to use.)

Using pizza cutter or sharp knife, cut out 2-½ × 4-inch rectangles of dough. Press broken or unused edges of dough together and roll as needed to form as many rectangles as possible, about 24.

Using thin spatula, place half of dough rectangles on prepared baking sheet. Fit as many as you can, leaving ½ inch between each. Add 1 to 2 tablespoons of fruit preserves in center of each. Place additional dough rectangle on top of each jam-covered slice and seal all four edges using fork, gently pressing down fork tines into both layers of dough. Using toothpick, pierce three or four holes on top of each pastry. Repeat until all dough is used. (Note: It’s OK if dough doesn’t seem completely sealed. There is no harm if some jam seeps out during baking.)

Bake 25 to 30 minutes, until very lightly golden around edges. Cool several minutes on baking sheet. Using spatula, transfer pastries to cooling rack to completely cool before icing.

In small bowl, whisk together soy milk and powdered sugar. (Note: Icing should be thick.)

Place paper towel or parchment paper below cooling rack to catch drips. Spoon icing onto middle of cooled tarts, drizzling it outward and allowing some to drip off sides. Add sprinkles before icing dries and hardens.