Preheat oven to 350.

In a small bowl, dissolve yeast in 2 cups warm water. (Use a thermometer, if possible. Otherwise, add 1 cup boiling water to 1 cup cold water.) Add 1/4 cup sugar, and allow the yeast to work for about 10 minutes while you prepare the dry ingredients.

Place flaxseeds and water in a blender and blend for about 2 minutes or until the mixture is the consistency of unbeaten egg white. Or grind the seeds in a spice mill or coffee grinder; place ground seeds and water in bowl of food processor and beat to desired consistency.

Place 6 cups flour, salt, remaining sugar and raisins (if using) in a large bowl.  Add flaxseed mixture, oil, agave and yeast. Mix until dough forms, adding more flour if needed. Turn the dough out onto a floured surface, flour your hands and knead the dough for about 10 minutes. Add flour as necessary until the dough no longer sticks to the board or your hands.

Oil a deep bowl. Put the dough in it, turning to grease it on all sides. Cover the bowl with a damp cloth or with plastic wrap, and allow to rise for about 1-1/2 hours, or until doubled in bulk.

Punch down and allow to rise a second time. Punch down again and knead briefly.  Use a heavy, sharp knife to cut the dough in half. Cover one half while you shape the first loaf. Oil a baking sheet. Divide one dough ball into three equal parts. Roll each one into a "snake," using a back and forth motion and keeping the dough under the palms of your hands. Each "snake" should be about 16" long. Allow them to rest a few minutes, then pinch the three strands together at one end, braid them, and pinch them together at the other end.

Remove the first loaf to an oiled baking sheet. Shape the second loaf, place it on the baking sheet, and allow the loaves to rise again.

For a crisp crust, brush loaves with cold water before placing in oven. Bake 25-35 minutes. The usual criterion for doneness is that the loaf sounds hollow when rapped on the bottom with your knuckles, or you may insert a thermometer in a crease on the bottom of the bread. It should register 200 degrees .

Cool loaves on a cooling rack. Makes 2 large loaves. Freezes well.

Preparation tip: You can make the dough the evening before and refrigerate it after the first or second rising. Extra dough can also be used for dinner rolls.

To form round challot for Rosh Hashana, and the first Shabbat of each month:  Divide the dough in two balls. Roll each one into a thick rope and coil the rope upon itself. If you prefer, divide the dough in thirds and make 3 loaves

Note: We love the tradition of dipping our challah into olive oil, particularly an olive oil which has been spiced with a bit of red pepper or other herbs, such as rosemary.