Heat olive oil in a large pot over medium-high heat. Season the oxtails with salt and black pepper. Sear the oxtails on all sides until browned, about 8-10 minutes. Remove and set aside.

Sauté Aromatics

In the same pot, add diced onion and cook until translucent, about 5 minutes. Add minced garlic and cook for another minute.

Simmer

Return the oxtails to the pot. Add beef broth, chipotle peppers, cumin, and oregano. Bring to a boil, then reduce heat to low and cover. Simmer for 2-3 hours, or until the meat is tender.

Cook Radiatori

Boil Pasta

While the oxtails are simmering, bring a large pot of salted water to a boil. Add radiatori pasta and cook according to package instructions until al dente. Drain and set aside.

Prepare Pickled Fennel

Pickle Fennel

In a saucepan, combine white vinegar, water, sugar, and salt. Bring to a boil, then pour over thinly sliced fennel in a jar. Let cool and refrigerate for at least 30 minutes.

Assemble Dish

Combine and Serve

Once the oxtails are tender, shred the meat and mix it with the sauce. Serve over the cooked radiatori pasta, top with shredded gouda cheese, and garnish with pickled fennel.