Peel and cut vegetables and place in a large skillet with a little oil and a tablespoon of each spice. Cook over low heat for a few minutes until golden brown. Place vegetables in a salad bowl and add finely chopped fresh coriander. Cut a brick sheet in half. Fold it in half lengthwise and place a tablespoon of browned vegetables in the leftmost part. Grasp the top left corner of the sheet and fold it down diagonally to form a triangle. Repeat alternately: move the bottom left end to the top right end, then the top left end to the bottom right end, and so on. Once the sheet is coming to an end, fold what is left of it inside the samossa to close it.
In a frying pan, sauté the samossas in a little oil a few minutes on each side before serving.