Make the dough:in a large mixing bowl, mix flour and salt. Add the oil and then start mixing with your fingers, rub the flour with the oil until the oil is well incorporated. Once incorporated, the mixture resembles crumbs.
Start adding water, little by little and mix until dough is formed. Cover the dough and let rest for 30 minutes.
Make the filling: in a bowl, mix all the filling ingredients. Set aside.
Divide the dough into 6 pieces. Roll out each piece very thinly.
Heat a skillet or tawa over medium heat. Cook each circle of dough for about 10 seconds on each side.
Cut each circle into rectangle, then cut into 6X18cm wide strips.
Fold each strip into a cone as described in the video, fill with onion filling. Brush the edges with water-flour mixture and seal the samosa.
Make the thick paste: in a small bowl mix flour and water until smooth paste is formed, is needed add more water or flour.
Heat oil to 350F (175C). Drop the samosas into hot oil, fry until golden brown, about 3-4 minutes.
Drain on paper towels before serving. Serve with your favorite sauce.