>From the World of Jewish Cooking by Gil Marks:

Dissolve the yeast in 1/4 cup of the water. Stir in 1 teaspoon of the sugar and let stand until foamy, 5-10 minutes.

Add the remaining water, remaining sugar, oil, margarine, or butter, eggs, and salt. Blend in 1 1/2 cups of the flour. Add the remaining flour, 1/2 cup at a time, until the mixture holds together.

On a lightly floured surface, knead the dough until smooth and elastic, about 10 minutes.

Place in a greased bowl, turning to coat. Cover with a towel or plastic wrap and let rise at room temperature until double in bulk, about 1 1/2 hours, or in the refrigerator overnight. (The dough is easier to handle when chilled, which is beneficial for cakes that require rolling.)

Pour down the dough.

Divide the dough into thirds. On a lightly floured surface, roll out each dough piece 1/4 inch thick. Cut out 3 to 4-inch rounds.

Place 1 tablespoon filling in the center of each dough round. Pinch the bottom side of the dough round together over the filling. Fold down the top flap and pinch the other two sides together to form a triangle, leaving some filling exposed in the center. (The hamantaschen can be prepared ahead to this point and frozen for several months. Defrost before baking.)

Place the cookies 2 inches apart on several greased baking sheets. Cover and let rise at room temperature until nearly double, about 1 hour.

Preheat the over to 350 degrees.

Brush the tops of the hamantaschen with a egg wash (consisting of 1 egg beaten with 1 tablespoon water). Bake until golden brown, about 25 minutes. Transfer to a wire rack and let cool completely.

Fillings:

Mohnfullung (Poppy Seed Filling): Combine the poppy seeds, water or milk, sugar, or honey, and salt in a small saucepan. Simmer over medium-low heat, stirring frequently, until the mixture thickens, about 10 minutes.

Remove from the heat and stir in the remaining ingredients. Let cool, and store in the refrigerator if not using immediately. Yields about 2 cups.