Onion and Poppy Seed Purim Ring

1. In a large bowl, whisk together the yeast and 3/4 cup of the flour, then whisk in the warm water until smooth. Let stand uncovered for 10 to 20 minutes, or until it begins to ferment and puff up slightly. 
2. Whisk the 2 eggs, oil, salt, and sugar into the puffed yeast slurry until the eggs are well incorporated and the salt and sugar have dissolved. With your hands or a wooden spoon, stir in the remaining 3 cups flour all at once. When the mixture is a shaggy ball, scrape it out onto your work surface and knead it until smooth and soft, no more than 10 minutes. (Soak your mixing bowl in hot water now to clean it and warm it if you would like to use if for fermenting the dough). 
3. Place the dough in the warm cleaned bowl and cover it with plastic wrap. Let the dough ferment until it has at least doubled in bulk, about 2 hours, depending on the temperature in your kitchen. 
4. Line a round pizza pan or a large baking sheet with foil and oil it generously, or line it with parchment, which needs no oil. 
5. When the dough has doubled in bulk, it is ready to shape; do not punch it down. Cut the dough into 2 pieces. Roll each piece into a 30-inch strand, then, using a rolling pin, roll each strand into a 30 by 4-inch rectangle. Spoon a heaping line of half the filling down the center of the dough. Pull the long edges up over the filling and pinch them together. Arrange the strands side by side, with the seams down. Beginning in the middle, cross 1 strand over the other, being careful to keep the seams facing down, and continue to cross the strands until you reach their ends. Pinch the ends together. Bring the ends around to form a ring and pinch the ends together. 
6. Carefully pick up the ring, place it seam side down on the prepared pan or sheet, and cover it well with plastic wrap. Let the ring rise until very soft and tripled in size, about 1 hour. Meanwhile, 30 minutes before baking, arrange an oven rack in the lower position and preheat the oven to 350 degrees F. 
7. Beat the egg with a pinch of salt for glazing the ring. 
8. When the ring has tripled in size and the dough does not push back when gently pressed with your finger but remains indented, brush it with the egg glaze. Sprinkle it with poppy seeds or sesame seeds, if desired. Bake for 45 to 50 minutes or until very well browned. After 30 minutes of baking, turn the pan around so that the ring browns evenly. When the ring is done, remove it from the oven and let it cool on a rack. 

Onion Filling:

1. Combine all ingredients in a bowl. Set aside until the bread is ready to be filled.