In medium saucepan, whisk the lemon zest, lemon juice, sugar and egg yolks.

warm water (100°F to 110°F).extra-virgin olive oil, plus more for greasing and brushing.

all-purpose flour, divided, plus more for dusting.(10-ounce) packages.frozen leaf spinach, thawed.

red onion, minced.Combine warm water, sugar, and yeast in a small bowl.

Let stand until foamy, about 10 minutes.

Add 1/4 cup oil to yeast mixture, and stir to combine.. Stir together 3 1/4 cups flour and 2 1/2 teaspoons salt in a large bowl, and make a well in center of dry ingredients.Add tomatoes, browned meat, oregano, and chicken stock.

Bring sauce to a simmer and cook 1 hour, stirring occasionally.Stir in butter and red wine vinegar.. Bring a large pot of salted water to a boil.

Add pasta and cook to almost al dente.Drain pasta and gently toss with sauce and little pasta cooking water, as needed, to loosen sauce.