1Put flour, sugar and salt into the mixing bowl of a Breville bench mixer. Make a dent in the center of the flour using the back of a spoon. In a separate bowl, combine warm water and yeast and let sit until foamy, about 5 minutes.
2Add yeast mixture to the mixing bowl and stir to combine. Whisk eggs, yolk and oil in a small bowl and add to the mixing bowl. Using the dough hook, knead on low speed until the dough comes together. Increase speed to medium-low and knead until dough is smooth and elastic, 6–8 minutes. Add the poppy seeds and knead until incorporated, 1–2 minutes.
3Turn dough onto a lightly floured surface and knead gently into a smooth ball. Place in an oiled glass bowl and cover with plastic wrap.
4Insert wire rack into rack position 8 and place bowl on the wire rack. Select PROOF/85°F/CONVECTION/45 minutes and press START. Proof the dough for 45 minutes or until doubled in size.
5Divide dough into 3 equal portions and roll each portion into a log 16 inches long. Cross the logs over each other to create a braid and tuck the ends under the loaf. Line roasting pan with parchment paper, letting it come up the sides. Place loaf diagonally on the paper and loosely cover with plastic wrap.
6Place roasting pan on the wire rack. Select PROOF/85°F/CONVECTION/45 minutes and press START. Proof the loaf for 45 minutes or until loaf has almost doubled in size.
7Remove roasting pan from oven and move wire rack into rack position 6. Press PHASE COOK, and then select BAKE/400°F/10 minutes. Press SELECT/CONFIRM to confirm the first cooking phase. Select BAKE/350°F/15 minutes for the second phase, and then press START to preheat oven.
8Mix egg white and 1 tablespoon water in a small bowl. Remove plastic wrap from pan and brush outside of loaf with egg wash.
9Once preheated, place the loaf in the oven and bake for 20-25 minutes or until loaf is deep golden brown and hollow-sounding when tapped.
10Transfer loaf to wire rack and let cool completely before serving.