1. Heat 2 tablespoons oil in 10-inch skillet over medium-high heat until shimmering. Add fennel and cook, stirring occasionally, until softened and browned around edges, 4 to 6 minutes. Add garlic, fennel seed, saffron (if using), pepper flakes, and orange peel; cook, stirring constantly, until fragrant, about 30 seconds. Stir in tomatoes and cook until tomato pieces lose their shape to form chunky sauce, about 10 minutes.

2. Remove and discard orange peel. Stir in orange juice, basil, salt, pepper, and sugar to taste. Toss sauce and remaining 2 tablespoons oil with pasta and serve.

Makes enough to sauce 1 pound of pasta