Crock Pot Pork Roast

Bahan-bahan (8 porsi)

• 5 to 6 pounds boneless pork shoulder roast (see notes for other cuts)
• 4 cloves garlic (thinly sliced)
• 1 ½ teaspoons salt
• 1 teaspoon black pepper
• 1 tablespoon vegetable oil
• 1 large yellow onion (sliced)
• 8 ounces cremini mushrooms (thickly sliced)
• 3 ribs celery (cut into 1-inch chunks)
• 2 medium carrots (cut into 1-inch chunks)
• 1 cup beef broth
• 1 tablespoon soy sauce
• 2 bay leaves
• prepared mashed potatoes (for serving)
• 3 tablespoons cornstarch (more as needed)
• 3 tablespoons cold water
• 1 beef bouillon cube (optional)