How to Make It
Season the pork with salt and white pepper, then slather it with the mustard. In a medium nonstick skillet, heat 2 tablespoons of the olive oil. Add the pork and cook over moderately high heat, turning twice, until browned, about 9 minutes. Transfer the pork to a plate.
Pour off the oil in the skillet. Add the milk, garlic and sage sprig. Simmer over moderately low heat until the garlic is almost tender, about 20 minutes.
Add the pork to the skillet along with any accumulated juices and simmer, turning the pieces every 5 minutes, until an instant-read thermometer inserted at the thickest point registers 140°, about 20 minutes. Transfer the pork to a plate. Cover with foil and keep warm. Discard the sage sprig.
In a blender, puree the milk with the garlic until smooth. Return the sauce to the skillet, stir in the minced sage and season with salt and white pepper.
In a medium bowl, combine the remaining 1 tablespoon of oil with the port and season with salt and white pepper. Slice the pork 1 inch thick and arrange on plates. Spoon the garlic-sage milk sauce on top. Garnish with the small sage leaves. Toss the spinach and strawberries in the dressing and serve the salad alongside the pork.