Roast the poblano chiles over an open gas range or broil. Turn with tongs for even roasting, about 5 minutes each. Make sure you get the chiles blackened and blistered all over. Be careful not to overcook so they have shape to hold the stuffing when baking. Place poblanos in a sealed, gallon size plastic bag and cover with towel for about 15 minutes.
Meanwhile, cook ground pork until slightly browed. Add cumin, cayenne, chili powder, salt, pepper, shallots, green onions, green chilies and corn. Cook for additional minute. Cool slightly.
Preheat oven to 375 degrees. Mix the pork mixture with the rice. Add the HIDDEN VALLEY RANCH DRESSING and stir. Remove chilies from bag. Using a paring knife, gently rub the skin off of the flesh of each chile. Wipe the surface of the flesh with paper towels to remove the excess skin.
Slit each poblano lenghtwise. Stuff the pork and rice mixture into poblanos. Lay chilies in a 3x5 dish. Bake for about 35 minutes. Sprinkle with additional Monterey Jack cheese and heat for another 3 to 5 minutes, until cheese is melted. Serve with avocado ranch sauce.
For the sauce:
Mash the avocados and mix in the rest of ingredients. Blend with a stick blender until smooth.