Mama Teresa's Vegetable Soup

Ingredients

• 1 rib celery cut into 1/2-inch pieces
• 1.3 teaspoons coarse gray sea salt 
• 1 large eggs 
• 1.5 tablespoons basil fresh chopped
• 1.5 tablespoons flat-leaf parsley fresh chopped
• 0.3 teaspoon coarsely ground pepper black
• 2 tablespoons olive oil plus additional extra-virgin for serving
• 1 small onion chopped
• 1 teaspoon oregano dried crumbled
• 2 tablespoons gratedparmigiano-reggiano plus additional for serving finely
• 6 oz plum tomatoes (2 or 3 medium)
• 3.5 cups water 
• 0.5 lb yellow-fleshed potato such as yukon gold 
• 2 medium zucchini quartered ()

Equipment

• bowl
• sauce pan
• knife
• whisk
• pot
• slotted spoon
• cutting board

Directions

1. Cut a shallow X in bottom of each tomato with a sharp paring knife and blanch tomatoes in a 2- to 3-quart saucepan of boiling water 20 seconds.
2. Transfer tomatoes with a slotted spoon to a cutting board and, when cool enough to handle, peel, beginning from scored end, with knife, then seed and chop.
3. Heat oil in a 4-quart heavy pot over moderately high heat until hot but not smoking.
4. Add onion and tomatoes, then reduce heat to moderate and cook, stirring occasionally, until onion is softened, 4 to 5 minutes.
5. Meanwhile, peel potato and cut into 1/4-inch dice.
6. Add potato to onion mixture along with zucchini and celery and cook, stirring occasionally, 5 minutes.
7. Add water, herbs, sea salt, and pepper and bring to a boil, uncovered. Reduce heat and simmer, uncovered, stirring occasionally, until vegetables are very tender, 30 to 35 minutes.
8. Remove from heat.
9. Whisk together egg and cheese in a bowl until combined well, then add to soup in a stream, stirring. Divide among 4 bowls and serve with olive oil and cheese.