Dough: Prepare dough by mixing flour, oil, lemon juice, water and salt. Sprinkle a handful of flour on a board and roll out the dough. Spread the margerine over the dough. Fold dough into thirds. Refrigerate for half hour, and then roll dough out again. Fold in thirds and return to refrigerator. Repeat rolling, folding, and refigerating 1 more time, then roll dough out into a large thin rectangle.
For cheese stuffing, mash the potatos and the egg. grated cheese and margerine. Mix well.
For Spinach Stuffing, cook the spinach in the water that clings to its leaves after washing, then drain and chop. Saute the garlic in the butter, then chop fine and add to spinach. Add lemon juice, salt and pepper and mix well.
To ASSEMBLE: Cut the dough into 3-inch sqaures. Place 1 tsp cheese or spinach stuffing (or 1/2 tsp of each) on each square, fold dough in half to form a triangle, and pinch edges to seal well. Brush each filled square with the beaten egg and sprinkle with the sesame seeds. Bake in a preheated 350 F. (moderate) oven until golden--approximately 30 minutes. Makes 12 pastries.