Saffron Tomato Sauce with Capers

Toss this saffron-scented sauce with pasta, stir it into steamed mussels or clams, or spoon it over sautéed or roasted fish, chicken, lamb, fennel, or cauliflower.

• 3 Tbs. extra-virgin olive oil
• One-half small yellow onion, finely chopped (about 1/2 cup)
• 2 large cloves garlic, very thinly sliced crosswise
• 30 threads saffron
• Pinch crushed red pepper
• 28-oz. can whole peeled plum tomatoes (preferably San Marzano), drained and small diced (about 2 cups)
• 2 tsp. capers, rinsed and lightly chopped
• 1 small sprig fresh thyme
• Pinch sugar
• Kosher salt and freshly ground black pepper
• 1 Tbs. chopped fresh parsley

Heat the oil in a 2-quart saucepan over medium heat until shimmering. Add the onion and garlic and cook, stirring occasionally, until soft but not browned, about 5 minutes. Crumble the saffron into the pan and stir in the crushed pepper. Let cook for about 20 seconds and then add the tomatoes, capers, thyme, sugar, 1/2 tsp. salt, and several grinds of pepper. Simmer briskly, adjusting the heat as necessary and stirring occasionally, until the tomatoes are softened and the flavors melded, about 15 minutes. Discard the thyme sprig and stir in the parsley. Season to taste with salt and pepper.