Place the pork cubes in a bowl or casserole dish.
In a small bowl, whisk together the garlic, olive oil, vinegar, salt and pepper until blended.
Pour the marinade over the pork and cover with plastic wrap.
Store in the refrigerator for a minimum of three, or up to eight hours.
Preheat the grill to medium-high heat.
Thread the meat, mushrooms, and sage leaves alternately onto the skewers.
Continue until all the ingredients are used.
Grill until golden brown, turning halfway. This should take about a total of 10 minutes. Brush with additional olive oil as needed to prevent sticking.
Serve with honey mustard sauce. Serve immediately.