In a medium mixing bowl, combine the flour with the salt. Add the oil and mix.
Start adding the water while stirring, until a dough forms. Set aside.
Heat 1-2 Tbsp of olive oil in a pan, then add the finely chopped garlic, cumin seeds, ginger, chili pepper, chili powder and chopped cilantro.
When the garlic develops some color, add the onion. Cook until translucent.
Chop the potatoes and add them to the pan.
Add the lemon juice and season with salt and pepper.
Cook for 5-7 minutes.
Cut the dough into 8 pieces.
Roll each piece into a circle and cut it in two.
Form the samosas and fill them with the potato mixture.
Deep fry in oil until golden brown.
Notes
To bake instead of fry, brush the samosas lightly with oil and bake at ~200C/400F until golden, turning once. Store leftovers in an airtight container and reheat in the oven to keep them crisp.