cut rabbit in 6-8 pieces
Season the rabbit with salt and pepper.
Heat a Dutch oven or large, deep, heavy pan over medium-high heat. Add the butter and oil. When sizzling hot, working in batches, sear the rabbit, about 3 to 4 minutes on each side, until nicely browned. Remove browned rabbit from pan and set aside.
Add the diced onion/shallot and sauté until softened and lightly browned, stirring occasionally, about 5 to 6 minutes.
Sprinkle onions with flour and stir until well incorporated, then cook for a minute or so until mixture starts to smell toasty. Add wine and 1 cup broth, whisking as the sauce thickens. Whisk in remaining broth and 1 tablespoon of mustard and bring to a simmer. Taste for salt and adjust.
Return browned rabbit pieces to the sauce. Add thyme and sage. Cover pot and simmer until meat is fork tender, about 45 to 50 minutes.
Using tongs, remove rabbit pieces from sauce, set aside, and keep warm. Put saucepan over medium heat and bring contents to a simmer. Whisk in crème fraîche, 1 tablespoon of mustard, and capers and simmer until somewhat thickened, about 5 minutes. Taste sauce and adjust seasoning.
Transfer rabbit to a warmed serving bowl and ladle the sauce over. Sprinkle with chives.
