From Annabel Karmel's First Meals. Tip: when handling phyllo pastry, keep the piece you are not working with covered with a damp dish towel to prevent it from drying out and becoming brittle and difficult to work with.
Heat the oil in a skillet, add the onion and garlic, and saute for 2-3 minutes. Stir in the spices and saute for 1 minute. Add the vegetables and cook for 5 minutes, stirring occasionally. Stir in the sugar and yogurt. Season and cook for 3-4 minutes.
Lay the phyllo pastry out flat and cover with a damp dish towel. Place one sheet of pastry on the work surface and brush with melted butter. Fold the pastry in half lengthwise and brush again with butter.
Place a tablespoon of filling on one end of the strip, leaving a 1 inch wide border around it. Fold over the corner to make a triange, then keep folding the package over on itself, along the length of the pastry. Seal the flap left at the end with melted butter. Repeat with the remaining sheets and filling.
Place the samosas on a lightly greased baking sheet and brush with more butter. Bake in a 350 degree F preheated oven for 20-25 minutes, or until crisp.