Preheat oven to 400 degrees. Place the barley in a pot of water with a large pinch of salt, bring to a gentle boil, and cook for 25 minutes, or until tender. Drain and set aside in bowl.
Meanwhile, mince the shallot and halve the Brussels sprouts.
In a bowl, toss the Brussels sprouts with 1 tablespoon olive oil, salt, and pepper.
Heat a cast-iron or oven-proof skillet over medium high heat. Place the Brussels sprouts cut side down on the skillet. Sear for two minutes, then transfer to the oven for 3-5 more minutes until softened.
Add the shallot, balsamic vinegar, honey, 1 tablespoon olive oil, watercress, and half the cranberries to the bowl with the barley. Toss to combine.
Serve the barley salad topped with Brussels sprouts, feta cheese, pepitas, and remaining cranberries.