Udon in Buttery Tomato and Soy Broth

Name: Udon in Buttery Tomato and Soy Broth
Ingredients: 2 large beefsteak tomatoes, halved crosswise, seeds removed; ¼ cup vegetable oil; 2 large onions, very thinly sliced; 4 garlic cloves, thinly sliced; 1 1 piece ginger, peeled, finely grated; 1½ tsp. freshly ground black pepper; 2 whole star anise; 1 3 cinnamon stick; Kosher salt; 2 7-oz. packages instant udon noodles, flavor packets discarded; 3 Tbsp. low-sodium soy sauce; 3 Tbsp. unsalted butter; Toasted sesame oil (for serving); 4 scallions, thinly sliced; ½ cup coarsely chopped cilantro leaves with tender stems