2 tablespoons olive or vegetable oil
2 large onions, chopped (2 cups)
4 medium carrots, chopped (2 cups)
4 cups sliced mushrooms
2 medium green bell peppers, chopped (2 cups)
4 cans (14 1/2 ounces each) diced tomatoes with basil, garlic and oregano, undrained
2 cans (15 ounces each) tomato sauce
2 cans (6 ounces each) Italian-style tomato paste
1 tablespoon sugar
1 teaspoon salt
1 teaspoon fennel seed, crushed, if desired
24 ounces uncooked spaghetti
Grated Parmesan cheese, if desired