Preheat a water bath to 131°F (55°C).
Lightly salt the rack of lamb. Combine the coriander and cumin in a bowl then sprinkle over the lamb. Evenly spread the orange zest over the meat then place the lamb in a sous vide bag with the rosemary. Seal the bag and cook for 2 to 4 hours.
For more information on the cooking times you can read my detailed article which addresses why is there a range in sous vide cooking times.
Put the pomegranate juice, orange juice, thyme, cinnamon, and ancho pepper in a pot over medium heat and lightly simmer for 20 to 30 minutes, until reduced and thickened. Remove from the heat, discard the cinnamon stick and ancho pepper then stir in the honey. The sauce can be made a day or two ahead of time and refrigerated, or left on the counter for an hour or two.
Cut the ends off of the Brussels sprouts and discard them. Cut the Brussels sprouts in half length-wise. Heat the olive oil in a pan over medium to medium-high heat. Add the Brussels sprouts and cook, stirring infrequently, until the Brussels sprouts start to brown.
Add the shallots, garlic, thyme, and water to the pan then cover it and let the Brussels sprouts steam until tender, 5 to 10 minutes. Remove the Brussels sprouts from the pan, toss with the lemon zest and squeeze the lemon over the top.
Remove the cooked rack of lamb from the bag, discarding the rosemary, and dry the meat off well. Quickly sear the lamb then cut it into serving sections, usually one or two ribs.
Place a few sections of lamb onto the plate. Arrange the Brussels sprouts and poached tomatoes around it. Drizzle the lamb with the pomegranate sauce. Add some pomegranate seeds and oregano leaves to the lamb, then sprinkle with some smoked salt.