Cook bones in a large Dutch oven over medium-high heat 8 minutes or until very brown, stirring occasionally. Add wine and next 6 ingredients; stir well, and bring to a boil. Reduce heat to medium, and cook, uncovered, 45 minutes or until stock is reduced to 1 1/4 cups. Strain stock through a sieve into a bowl; discard solids. Add mustard to stock; stir well, and set aside.
Trim fat from venison. Sprinkle salt and pepper over venison. Heat oil in a large nonstick skillet over medium-high heat. Add venison, and cook 15 minutes or until a meat thermometer registers 140° (medium-rare), browning venison on all sides. Remove venison from skillet; set aside, and keep warm. Wipe drippings from skillet with a paper towel.
Add 1/2 cup gin to skillet; cook over low heat until warm. Ignite with a long match. Add stock to skillet; bring to a boil. Spoon sauce on individual plates. Cut venison into 1/8-inch-thick slices, and arrange slices on top of sauce.