For the onions and apples: Saute the onions in a nonstick pan over medium-high heat in the butter for 1 to 2 minutes, and then add the apples. Add in the sage, thyme, garlic, brown sugar, salt, pepper and apple juice, and then squeeze the lemon half into the mixture. Cook and gently stir until the apple juice is reduced and the onions are translucent, about 5 minutes. Add the spinach to the mixture, cover the pan and cook until the spinach is wilted, about 2 minutes. You don't want to overcook the spinach, just wilt it. Taste for seasoning.

For the pork: Preheat the oven to 375 degrees F.

Place an oven-proof saute pan over medium-high heat and melt 1 tablespoon butter. Sprinkle the pork with salt and pepper and, with tongs, place the loin in the hot butter. Brown the pork thoroughly on all sides, 7 to 8 minutes total.

Top the pork with the sage leaves, thyme (be careful as the thyme might crackle) and garlic. Add the remaining 1 tablespoon butter and place in the oven. Cook the pork 20 to 30 minutes, but make sure to not overcook. The internal temperature should read 160 degrees F on a meat thermometer. (If you are concerned about overcooking, turn the oven onto warm while finishing the rest of the dish.) Transfer the pork to a platter, tent with some foil and let rest. Remove the whole leaves from the saute pan.

For the gravy: In the pan you browned the pork, melt the butter over medium to medium-high heat. Sprinkle the flour into the hot pan juices and whisk together to make a roux. Continue to whisk and cook the roux until turns light brown, about 5 minutes. Whisk in the apple cider and continue to stir. Pour in chicken broth and boil the mixture until the gravy is thick, 5 to 7 minutes depending on desired thickness. Squeeze the lemon half into the mixture. Taste for seasoning (salt, pepper, etc). Sprinkle in the torn tarragon leaves. Finish by whisking in the cream.

To serve: Divide the onion-apple saute among 4 plates. Slice the pork and divide over the onion-apple saute. Cover the pork with gravy. Garnish with some thyme and a wedge of lemon. Serve with cous cous and asparagus.