1 tablespoon expeller-pressed canola oil
1 onion, diced
4 garlic cloves, finely chopped
2 serrano chiles, finely chopped (remove the seeds first for milder flavor)
1 teaspoon black mustard seeds
3/4 teaspoon cumin seeds, plus extra for topping the samosas
3/4 teaspoon garam masala
1/2 pound peeled, deveined medium shrimp (31/40 count), chopped
1 small mango, diced (about 1 cup)
3/4 teaspoon fine sea salt
1/3 cup chopped fresh cilantro
1 (16-ounce) tube biscuit dough
Flour, for rolling dough
In a large skillet, heat oil over medium-high heat. Add onion and garlic and cook, stirring frequently until softened, about 5 minutes. Stir in chiles, mustard seeds, cumin seeds and garam masala and cook, stirring until fragrant, about 1 minute. Stir in shrimp, mango and salt, and cook until shrimp are just cooked through, 4 to 5 minutes. Remove from the heat, transfer to a bowl and stir in cilantro. Allow to cool.
Remove dough from tube in one piece and slice into 12 equal pieces. On a lightly floured surface, roll each piece out into a circle about 4 inches in diameter. Place a scant 1/4 cup of filling on the bottom half of each circle, fold top over filling and pinch edges to seal. Place samosas on the baking sheet and press down on the sealed edges of each with the tines of a fork to crimp. Pinch the rounded edge of each samosa into a point to make a triangle shape and sprinkle with cumin seeds. Bake until dough is deeply browned, 15 to 17 minutes. Cool 10 minutes before serving.