Rosemary and Black Olive Focaccia Bread

1/2 cup onion, finely diced
3 T Olive Oil, divided (can use infused sundried tomato oil for a fantastic flavor)
2 T. freshly chopped rosemary
1 T. garlic, minced
1/2 cup black olives, pitted, and roughly chopped
1 1/4 cups warm water
1 - 1/4 oz. pkg. active dry yeast
1 t. unbleached cane sugar
3 - 3 1/2 cups unbleached flour
1 t. sea salt, divided
1 T. dried red bell peppers (opt.)
1/4 cup cornmeal, divided
1/4 cup vegan mozzarella cheese (opt.)