Coat a large heavy bottom skillet or dutch oven, with olive oil. Place sliced onion in the bottom.
Rub Turkey on all sides with oil ( or butter) and generously salt and pepper, both sides.
Place in the oven and immediately turn oven down to 400 F, and bake for 40 minutes.
In the mean time make the glaze.
Place ½ Cup of the blueberries (saving the rest), the sliced figs and and the balsamic in small sauce pan.
Bring to a simmer, then turn heat to low, or medium low, uncovered, keeping at a very gentle simmer, stirring occasionally until reduced by half.
Stir in maple syrup, whole grain mustard and a pinch of salt and pepper.
After the turkey has cooked 40 minutes, brush the turkey with the glaze and pour the rest over the top. Give the pan a shake. Surround the turkey with the remaining blueberries and sprigs of rosemary and continue roasting in the oven, lowering heat to 350, until it reaches 160F, 20 or more minutes, depending on the size.
Pull form the oven and let rest 5-10 minutes before serving.