Classic Thick Tomato sauce

Classic Thick Tomato sauce

1/4 cup olive oil
1 large onion, chopped
1 cup celery, diced
10 lbs. plum tomatoes, peeled
2 potatoes
2 carrots, peeled
1 tsp. salt
1 tsp. dried oregano
2 large sprigs fresh basil
2 large sprigs fresh parsley
1/4 tsp. fresh ground pepper

Heat oil over medium heat in large saucepan, cook onion and celery until soft, about 6 minutes. In blender, finely chop tomatoes in batches. Add tomatoes, potatoes, carrots, salt, oregano, basil, and parsley to saucepan. Reduce heat and simmer, uncovered, for three hours or until reduced by a and sauce is thick. Remove herb sprigs and discard. Remove potatoes and carrots, mash, and return to sauce to add thickening.