1. In a large saucepan cook 1 cup chopped onion in 1 Tbs. hot olive oil over medium heat until tender, about 8 minutes. Add 1 sliced garlic clove. Cook and stir for 1 minute. Add one 28-oz. can plum tomatoes, cut up and undrained, 2 cups water, 1 1/2 cups torn sourdough bread, 1/2 tsp. kosher salt, 1/2 tsp. each dried oregano and fennel seeds, and 1/4 tsp. crushed red pepper. Simmer, uncovered, for 10 minutes, stirring occasionally. Stir in 2 Tbs. unsalted butter. Let cool slightly. Blend or puree until smooth. Meanwhile, lightly coat 4 sourdough bread slices with 1 Tbs. basil pesto. Divide 1/2 cup grated sharp cheddar cheese between 2 slices. Cover with remaining bread, brush with 1 Tbs. olive oil and brown in a large skillet over medium heat until cheese melts, 2 to 3 minutes per side. Cut each sandwich into 1/2-inch "fingers" for dipping into soup.