Mix sage, salt, pepper, and garlic together in a small bowl and rub over the loin. Place in the bottom of the slow cooker along with 1/2 cup water. Cook on low for 6 hours. Remove from slow cooker and shred.
For the Sauce:
Just before the pork is done, place the sauce ingredients in a small pan. Cook over medium heat for 4 minutes or until the sauce thickens, stirring occasionally. Remove from heat and drizzle over shredded pork. Serve.