As you expand the well, keep pushing the flour up from the base of the mound to retain the well shape. The dough will come together when half of the flour is incorporated.
Start kneading the dough with both hands, using the palms of your hands. Once you have a cohesive mass, remove the dough from the board and scrape up and discard any leftover bits. Lightly reflour the board and continue kneading for six more minutes. The dough should be elastic and a little sticky. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature.
Roll the pasta out on a pasta rolling machine to the desired thickness.
In a mixing bowl, stir together the crab, half the scallions, and basic tomato sauce until well blended.
Cut pasta into 4-inch squares and place 1 tablespoon filling in center. Fold into triangles, exude the air and seal edges. Bring points of long side together to form a ring and seal with pressure between fingers. Cook the tortelloni in the boiling water for 8 to 10 minutes.
Meanwhile, in a 12 to 14-inch saute pan, melt the butter with the poppy seeds. Drain the cooked tortelloni carefully and gently place in pan. Add remaining scallions and toss to coat. Season with salt and pepper and serve immediately.
Yield: 4 cups