Heat 2 tablespoons of vegetable oil in a large skillet over medium heat.
Add the finely chopped onion, garlic, and ginger. Cook until the onions are soft and translucent, about 5 minutes.
Stir in the diced potatoes, cooked ground meat (or lentils), frozen peas, and all the spices (cumin, coriander, turmeric, paprika, chili powder). Cook for another 5 minutes until everything is well combined and heated through.
Season with salt and pepper to taste, then add the chopped cilantro or parsley. Remove from heat and let the mixture cool.
In a mixing bowl, combine the flour and salt.
Add the vegetable oil or melted butter and mix until the mixture resembles coarse crumbs.
Gradually add water, a little at a time, mixing until a smooth and pliable dough forms. You might need slightly more or less water depending on the flour.
Divide the dough into small balls and roll each ball out into a thin circle (about 6 inches in diameter) on a lightly floured surface.
Cut each circle in half to form semi-circles.
Fold each semi-circle into a cone shape, sealing the edge with a little water.
Fill the cone with the prepared filling, then seal the top edge to form a triangle shape. Pinch the edges to ensure they are well sealed.
Heat vegetable oil in a deep fryer or large pan to 350°F (175°C).
Fry the samoussas in batches, being careful not to overcrowd the pan, until they are golden brown and crispy, about 3-4 minutes per batch.
Remove from the oil and drain on paper towels.
Enjoy your meal!