Heat oil in a large skillet over medium-high heat. Season pork with salt and black pepper and add to hot pan. Cook 2 minutes per side, until golden brown. Remove pork from pan and set aside. In the same pan, add shallots and cook for 2 minutes, until soft. Add thyme and tarragon and cook 1 minute, until fragrant. Add wine or broth and cook 1 minute. Whisk flour into milk and add to pan. Return pork to pan and simmer 3 to 5 minutes, until pork is cooked through and sauce thickens.