Begin the coq au vin recipe by heating a dutch oven on medium-high heat and sauteing the bacon in hot butter slowly until lightly browned. Then remove bacon and set aside.
Dry chicken and season with salt and pepper. Sear chicken skin side down in the reserved bacon fat until golden brown, about 2-3 minutes, then brown on other side for another 2 minutes. Once done, remove and set aside.
In the same pot, add chopped garlic and herbs and stir through. Then add tomato paste and stir everything together.
Add the chicken and bacon back to the pot and pour in red wine and broth. There should be enough liquid to just cover the chicken. Place lid on pot, leaving a small opening and bring to a boil, then down to a simmer and cook for about 25-30 minutes, until chicken is cooked through and sauce has slightly reduced.
While the coq au vin is cooking, prepare the onions and mushroom. In a wide skillet, add butter and oil over medium heat along with the pearl onions, mushrooms and herbs. Pour in red wine and sautee for about 10 minutes, until mushrooms begin to soften and wine reduces.
Now to make the thickening agent, the "beurre manie". In a small bowl, blend together the flour and butter to form a paste. Add some of the liquid to the paste and whisk together, then add back into the coq au vin.
Add the onions, mushrooms and bay leaf to the casserole and baste with the sauce. Before serving, bring to a slow simmer so everything is heated through.
Recipe adapted from Mastering the Art of French Cooking