In a large bowl, dissolve the yeast in the water. Let sit 10 minutes, until bubbly.
Add the margarine or shortening, sugar, salt and flour.
Mix and knead in the bowl until the dough can be gathered into a ball, then knead on a counter until smooth and elastic, about 6 minutes. Coat lightly with olive oil, return to the bowl, and let rise until doubled in bulk, about 1 1/2 hours or up to 2 1/2 hours.
Punch down the dough and divide it into six balls. Let sit for 15 minutes.
Preheat the oven to 400 degrees.
Roll out each ball into a 12-inch round. As you do this, sprinkle each round all across the top with water, then with some of the seeds. Pass the rolling pin over the top two more times to press in the seeds and keep them from popping off as the bread cooks.
Place on individual baking sheets and bake until bubbled up and golden in spots, about 8 minutes.
Serve warm, at room temperature, or softened.
To soften lavosh, dampen on both sides by moistening it under tap water. Shake off the excess water and wrap the bread in damp kitchen towels. Place in a plastic bag. Set aside for 45 minutes to 1 hour, until soft enough to tear into pieces. Or let sit for 2 hours, until soft enough to roll up without tearing.
Note: Instead of the traditional sesame seeds, you can top the lavosh with caraway seeds, cumin seeds, nigella seeds or flax seeds.