1 pound French green beans, stems trimmed
1/4 pound thick-cut bacon, cut in 1/4-inch pieces
1 shallot, finely chopped
1/2 cup walnut halves and pieces, toasted
1 handful fresh flat-leaf parsley, leaves chopped
1 tablespoon grainy mustard
1 tablespoon hot water
Pinch sugar
1 lemon, juiced
Kosher salt and freshly ground black pepper
1/3 cup extra-virgin olive oil