Adjust oven rack to middle position and heat oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, combine mashed black beans, jerk seasoning (or all seasoning ingredients if making from scratch), and breadcrumbs. Stir until evenly combined.
Unfold each puff pastry sheet onto a lightly floured surface. Cut each sheet into 4 equal rectangles (8 total). Spoon 3 to 4 tablespoons bean mixture onto one half of each rectangle, leaving a ½-inch border. Fold pastry over filling to form a rectangle or a triangle. Press edges with a fork to seal.
Place patties on prepared sheet. Brush tops lightly with plant milk or oil. Bake until golden brown and crisp, 25 to 30 minutes, rotating the sheet halfway through baking.
Serve warm on buns, in wraps, or over salad greens.
Notes
For extra crunch, pan-fry baked patties in a lightly oiled skillet over medium heat for 1 to 2 minutes per side. Optional — does not affect cooking time listed.
Substitute taco seasoning for a milder, Tex-Mex profile.
Keep puff pastry cold during assembly for best flakiness.