Combine the flour, sugar, zests, yeast, and salt in the mixing bowl of your stand mixer or large bowl.
4¼ cups (530 grams) unbleached bread flour, 2 tablespoons granulated sugar, zests of 1 orange and ½ lemon, 2¼ teaspoons instant yeast, 1 teaspoon salt
Measure out the water in a large-ish (2 cup is ideal) measuring cup. Add the two whole eggs, two egg yolks, and oil, and whisk lightly until uniform.
¾ cup (177 grams) lukewarm water, 2 eggs, whole, 2 eggs, separated, 2 tablespoons canola, safflower, or other neutral-flavored vegetable oil
Add the wet ingredients to the mixing bowl, and mix on low speed using the paddle attachment until combined.
Switch to the hook attachment and mix on medium speed for 6 minutes, adding small amounts of water or flour as necessary to get the dough to clear the sides of the bowl. The final dough should be soft and not sticky at all. It should pass the windowpane test if you do that sort of thing.
Add the raisins and mix on low speed or by hand until incorporated, about 1 to 2 minutes.
½ cup raisins
Form the dough into a round, lightly oil a bowl, cover with plastic wrap, and let rise in a warm, draft-free place until about doubled, about 1 hour (Rise #1 of 3).
Degas, re-form into a round, and again let rise until about doubled, about 1 hour (Rise #2 of 3)
Divide into three or five equal strands and braid the dough. Please see the main post text for more instructions. Let rise until doubled again (Rise #3 of 3).
At least 30 minutes prior to baking, preheat the oven to 325℉.
Right before baking, brush the loaf with the reserved egg whites (keep for one more brushing).
Bake on a middle shelf for 20 minutes. Brush one more time with reserved egg whites to ensure coverage of the entire loaf.
Continue baking until internal temperature is 190 to 195°, the crust is a rich caramel brown, and the bottom sounds hollow when thumped. This should take about 40 to 60 minutes in total, depending on the size of your loaves, whether you are using a pan, etc.
Cool for at least one hour if you can!