In a large mixing bowl, dissolve the yeast in the warm water. (Hot water from the tap, but no hotter).
In a saucepan, melt the butter. Add the milk and heat until it is warm. You can test it by putting a drop on your wrist. It should feel warm but not hot. If it is hot let it cool. The hot liquid will kill the yeast and your bread won't rise.
Add the milk and butter to the yeast and mix.
Add the sugar, 2 lightly beaten eggs, salt and lemon zest (if using). Mix to combine.
Add 5 cups of flour one cup at a time, mixing in between each addition. The dough will be a bit sticky.
Sprinkle about 1/2 cup of flour on the counter. Turn the dough out onto the floured surface and knead for about 5 minutes. Add extra flour, about 1/4 cup at a time, if the dough is too sticky too knead.
If you add too much flour the dough will not be light and fluffy. If you have a mixer with a bread hook use it to do the kneading.
Put the dough in a lightly oiled bowl. Cover with lightly oiled plastic wrap. Put in a warm place to rise until doubled, 1 to 1 1/2 hours
I put mine in the oven with the oven light on.
While the dough is rising, boil 1 1/2 cups water.
Get three small cups. Add 15-20 drops of color to each cup (one red, one yellow, one blue). Add 1 teaspoon vinegar to each cup, then add 1/2 cup of boiling water to each cup and stir.
Dip the eggs in the color and let sit until as dark as you want. You can mix and match the colors to have orange, green and purple too.
Punch down the dough and divide into 3 equal parts. Roll each part into a long rope, about 20 inches long.
Braid the three strands together and shape into a circle, pinching and tucking the ends together. Put it on a greased baking sheet.
Gently push the five colored eggs in the dough. Stick a small cup in the middle to keep the wreath from closing in the middle when it rises.
Let rise until doubled, about 45 minutes to 1 hour.
Preheat oven to 350 degrees.
Remove the cup from the center of the bread. Combine the last egg with 1 teaspoon water and brush on the bread (not the colored eggs). Cover all the dough, including in the crevices between the braid if possible.
Bake for 25 minutes until bread is golden brown.