This is the only recipe I could find, under the title "Sheepherder's Bread" from The Best of Sunset. Not knowing what Francisco bread looks like, I hope this is similar to what you are looking for, recipe wise. Sour dough bread would need a 'starter', unlike this bread which is a straight forward recipe.

SHEEPHERDER'S BREAD

Prep. Time ~ About 1 hr.
Rising Time ~ About 2-/2 hrs.
Baking Time ~ About 50 min.

As they tend their flocks in remote Western rangelands, Basque shepherds still bake big loaves of bread in Dutch ovens buried in pits. The same simple bread can also be baked in a conventional oven--with much more predictable results. To produce the unique dome shape and ring-pattern top, you'll need a 5-quart cast-iron or cast-aluminum covered Dutch oven.

Makes 1 very large loaf, 24 to 25 servings.

3 cups very hot tap water
1/2 cup (1/4-pound) butter or margarine
1/3 cup sugar
2 teaspoons salt
2 packages active dry yeast
About l9 1/2 cups all-purpose flour
Salad oil

In a large bowl, combine hot water, butter, sugar, and salt. Stir until butter is melted; let cool to about 110 degrees F. Stir in yeast and set in a warm place until bubbly, about 5 minutes.

With a heavy spoon, beat in about 5 cups of the flour to make a thick batter. Stir in about 3 1/2 cups more flour or enough to make a stiff dough. Turn dough out onto a floured board; knead until smooth and satiny, 10 to 20 minutes, adding more flour as required to prevent sticking. Place dough in a greased bowl; turn over to grease top. Cover with plastic wrap and let rise in a warm place until doubled, about 1 1/2 hours.

Punch dough down and knead briefly on a floured board to release air; shape into a smooth ball. With a circle of foil, cover the inside bottom of a 5-quart cast-iron or cast-aluminum Dutch oven. Grease foil, inside of Dutch oven, and underside of lid with oil.

Place dough in Dutch oven and cover with lid. Let rise in a warm place until dough pushes up lid by about 1/2 inch, about 1 hour (watch closely).

Bake, covered with lid, in a 375 degree oven for 12 minutes.

Remove lid and continue to bake until loaf is golden brown, 30 to 35 more minutes. Remove from oven and turn out of pan onto a rack (you'll need a helper). Peel off foil, turn loaf upright, and let cool.