Combine warm water, 1 tsp sugar and yeast in a bowl and allow to rise, About 10 minutes.
Combine, salt, 1 tsp sugar and both flour in a large mixing bowl and stir. The result will be a sticky, rough dough. If using a stand mixer, beat at medium speed for about a minute. Otherwise just use a spoon to stir until well combined.
Lift the dough out and lightly grease the bowl with nonstick spray or olive oil. Cover with a damp cloth, and set aside to rise until doubled. I heat my towel in the microwave, cover the dough and let it sit in the microwave while it’s rising. It takes about 45 minutes. The best though, is slow, cool rise over time to develop the flavors. To do so, put the dough in a bowl and set aside for 12 - 18 hours.
Once risen, lightly sprinkle the dough with flour and transfer to a floured work surface. Flatten the dough into a rectangle and spread basil and onions over the dough surface. Fold 1/3 on the rectangle in, then fold over the other half. Repeat steps to form a ball of dough.
Return dough to the bowl and repeat Step 3.
Preheat oven to 450°F while the dough rests. Place a metal or cast iron pan (not glass, Pyrex, or ceramic) on the lowest oven rack, and have 1 cup of hot water ready. Don’t put it in the pan yet.
After the second rise, remove dough from the bowl and form into a lovely round (or two small rounds, or whatever shape you would like). Place formed bread onto a lightly greased baking sheet, or baking stone.
Sift a light dusting of flour over the bread and slash the bread 2 or 3 times with a knife, making a cut about ½-inch deep.
Place bread in oven and carefully pour hot water into the shallow pan on the rack beneath. Expect it to bubble and steam; then close oven door quickly. The steam while baking will make the bread beautifully moist inside.
Bake the bread for 20 to 30 minutes, or until deep, golden brown.
Remove the bread from the oven and cool on a rack.