Start with the dough. Combine flour, salt, carrom seeds, baking soda, and oil in a bowl and mix until the ingredients are well combined. Then, add water a little at a time until the dough is soft but not sticky. Knead the dough for about 5 minutes, then cover it and set it aside to rest for 30 minutes.
While the dough is resting, prepare the filling. For this recipe, I like to use potatoes and spices like cumin, coriander, and fennel seeds, green chiles, chaat masala, ginger. You can really use any filling you like though - chicken, lamb, or even just mix vegetables would be delicious.
To assemble the samosas, divide the dough into 12 equal pieces. Roll each piece into a ball, then flatten it into a disc. Place 2 tablespoons of filling in the center of each disc, then fold up the edges to form a triangle. Pinch the edges together to seal them well.
Heat oil in a deep fryer or a heavy-bottomed pot. When the oil is hot, carefully add the samosas and fry them until they're golden brown and crispy.