Add onion to the pan and cook, stirring often, until softened and starting to brown, 3 to 5 minutes. Add garlic, crushed red pepper, and the crushed fennel seeds; cook, stirring, until fragrant, 30 to 60 seconds. Add orange juice and bring to a simmer. Cook for 1 minute. Add tomatoes and bay leaf; return to a simmer. Cook for 1 minute, mashing the tomatoes with a potato masher.