Sift flour and salt into a bowl, add oil and warm water and mix thoroughly, until ingredients are combined. (Add a little more water if necessary to combine ingredients.) Knead for about 10 minutes or until dough is elastic. Cover with plastic wrap and set aside while preparing filling.
Heat oil in a saucepan and fry garlic, ginger and half the onion until onion is soft. Add curry powder, salt and vinegar, mix well. Add minced steak and fry over a high heat, stirring constantly until meat changes color.
Turn heat down and add hot water. Cover pan and cook until meat is tender and all the liquid has been absorbed. Towards end of cooking, stir frequently to prevent meat from sticking to base of pan. Sprinkle with garam masala and chopped mint or coriander, remove from heat and allow to cool. Mix in reserved chopped onion.
Take small pieces of dough, shape into balls and on a lightly floured board roll each one thinly to a circle, the size of a saucer. Cut each circle in half.
Put a teaspoon of filling on one side of each half circle and brush edges with water. Fold dough over and press edges together firmly. You will now have triangular shaped samoosas.
When they are all made, heat oil in a deep pan and deep fry a few at a time until golden brown on both sides. Drain on absorbent paper and serve hot.
NOTE: Both samoosa and singara can be made using spring roll wrappers. Cut into 2 1/2 inch strips the length of the pastry. Put a teaspoon of filling at one end and fold the pastry over diagonally, then fold again and again, still keeping a triangular shape. Moisten end of strip with water or beaten egg and press lightly.