Place canola oil in a large pan over high heat.
Combine the rosemary, flour, salt and pepper.
Rub this mixture into the roast.
Brown roast in the pan.
Reserve by putting the roast on a roasting rack set into a roasting pan.
Place into a 450 degree oven for 20 minutes.

Add onions and garlic to a saute pan, cook until lightly colored.
Add the Calvados and cider and reduce by half at a medium boil.
Pour this mixture into the roasting pan.
Turn oven down to 350 and cook for 90 more minutes, basting each half hour with the onion mixture.

When roast is 160 degress on a meat thermometer, it is done.
Serve with the pan juices spooned over.