CUT 3 strips of bacon into 1/4 -in. pieces. Cook in a deep pot over medium until crisp, about 3 min. Remove bacon and discard all but 1 tbsp fat. Trim tough ends and ribs from 1 bunch kale (about 500 g). Coarsely chop leaves. Add to pot with 1/2 cup water. Cover and stir occasionally until wilted, 5 to 8 min. Stir in 2 tbsp Dijon mustard and top with bacon.