Turn the pork roast upside down and insert the garlic slices into the loose flesh. Sprinkle the roast with the fennel seeds and black pepper. Season the meat generously with salt and drizzle a little olive oil over it. Strip the leaves from a rosemary sprig or two, chop them roughly, and sprinkle them over the pork. Massage the seasoning into the roast.
Line a roasting pan with rosemary