DOUGH: Whisk flour and salt in a medium bowl. Add oil and rub it into flour with your fingers until mixture resembles coarse meal. Drizzle in water until dough can be gathered into a stiff ball.
Oil a large bowl and set aside. Knead dough on a clean surface for about 5 minutes, until smooth and supple. Form dough into a ball, transfer to prepared bowl, and cover with plastic wrap. Set aside for at least 30 minutes.
FILLING: Warm ghee in a medium skillet over medium heat. Add onion and a pinch of salt and cook for 5 to 7 minutes, until soft and translucent. Add garlic, jalapeño, and ginger and cook for 2 more minutes. Stir in curry powder and cook, allowing spice to bloom, for another minute.
Salt paneer well and add to skillet. Cook for 2 to 3 minutes over medium-high heat. Transfer mixture to a medium mixing bowl, then add cilantro and lemon juice. Stir to combine and season to taste.
TO ASSEMBLE: Divide dough into 6 equal balls and cover all but one with plastic wrap. Roll out ball on a clean work surface to a 7-inch round. Cut in half and set aside so dough can relax. Meanwhile, roll out a second ball. Returning to first round, wet edges of one half and fold it to form a cone shape (rounded edges should overlap). Press cut edges together to seal. Fill cone with 1½ to 2 tablespoons filling, close, and pinch to seal. Repeat process with remaining dough.
Pour about 2 inches of vegetable oil into a large, heavy-bottom pan. Heat oil to 350°F. Working in batches, carefully drop samosas into pan and reduce heat to low. Fry samosas until golden brown on both sides, turning as necessary. Transfer to a paper towel–lined plate. (Alternately, heat oven to 375°F. Arrange samosas on a rimmed baking sheet, brush lightly with oil, and bake for 20 to 25 minutes, until golden brown.) Serve immediately with chutney.