2 oz. thinly sliced pancetta or bacon
2 tsp. confectioners’ sugar
7 oz. Brussels sprouts, trimmed
5 tbsp. half & half
3 tbsp. apple cider vinegar
1 1⁄2 tsp. Colman’s hot English mustard
1⁄4 tsp. granulated sugar
Sea salt and freshly ground black pepper, to taste
1⁄2 cup walnuts, toasted and roughly chopped
2 stalks celery, sliced ¼” thick on the bias
1 small tart apple, such as Granny Smith, cored and cut into ¼” matchsticks
Heat oven to 350°. Place pancetta on a parchment paper-lined baking sheet and sprinkle with confectioners’ sugar; bake until crisp, 6–8 minutes. Bring a 4-qt saucepan of water to a boil. Peel and reserve outer leaves from sprouts, leaving the tender core. Using a mandoline (or your knife skills,) thinly slice cores; place in a bowl. Cook outer leaves for 1 minute; drain and transfer to a bowl of ice water. Drain and pat leaves dry using paper towels; add to bowl with cores.
In another bowl, whisk half & half, vinegar, mustard, granulated sugar, and salt; pour over sprouts. Stir in half each of the walnuts, celery, and apple, salt and pepper; transfer to a serving platter. Garnish with remaining walnuts, celery, and apple; crumble reserved pancetta over the top.