Preheat oven to 180°C (350°F).

Season the pork shank with salt and pepper and lightly coat with flour.

Warm a skillet over medium heat. Add 30 mL (2 tbsp.) of oil and 30 mL (2 tbsp.) of butter. When the oil and butter are very hot, brown shank about 5 minutes per side. 

Remove shank from skillet and set aside. Reduce heat to minimum. Add 30 mL (2 tbsp.) olive oil and 30 mL (2 tbsp.) of butter to skillet. 

Add garlic, onion, carrots, celery, bay leaf, thyme, and rosemary. Sauté vegetables to soften, about 5 to 7 minutes. 

Deglaze with white wine and reduce until liquid has almost completely evaporated. Add half the zest and lemon juice (about 1 lemon).

Pour in 625 mL (2½ cups) broth and bring to a boil. Transfer to a Dutch oven, add reserved pork shank, and cover. 

Cook until meat becomes very tender, about 2 hours. Add more broth if liquid evaporates too quickly

To finish, remove shank from Dutch oven, reduce sauce until texture becomes syrupy, and then add remaining lemon zest and juice and 2 tbsp. butter. Return pork to Dutch oven to reheat before serving.