Combine water, sugar and yeast in the bowl of a stand mixer; let sit 5 minutes until foamy.

Add flour, salt and butter; stir to combine. Using a dough hook, knead dough on medium speed 5 minutes until smooth, elastic and slightly tacky (or turn out onto a lightly floured surface and knead by hand 10 minutes).

Shape dough into a ball and place in a large, lightly greased bowl. Cover with lightly greased plastic wrap and let rise in a warm place 1 hour until doubled.

When dough is nearly doubled, combine water and baking soda in a large stockpot. Bring to a boil. Heat oven to 400 degrees F.

Punch down dough. Roll out on a lightly floured surface to ¼-inch thickness. Use a round biscuit or cookie cutter to cut out circles of dough, re-rolling scraps as needed.

Spoon a teaspoon or so of jam into the center of half the dough circles. Top with a piece of brie. Top with another dough circle to form a pie; use fingers or fork tines to seal the edges. Transfer pies to a lightly floured baking sheet or platter.

Place about 3 hand pies at a time in the boiling water bath; boil 30 seconds. Using a slotted spoon, remove pies and transfer to a parchment paper or silicone mat-lined baking sheet. Repeat with remaining pies, placing pies about 1 inch apart on baking sheets.

Lightly brush tops of pies with egg wash, then sprinkle with sea salt. Bake 12 to 14 minutes until golden brown and puffed. Cool slightly on a cooling rack before serving.