Freshly ground black pepper, and sea salt to taste
Trim excess fat from bacon, cut into 1-inch sections. Add bacon to large heavy-bottomed skillet. Cook over medium low heat until edges curl and bacon crisps, about 8 minutes. Place bacon on paper towels. Remove rendered bacon fat.
Remove fibrous stems, cut or tear kale crosswise into small strips. Combine olive oil with rendered bacon fat, heat for 1 minute. Add kale to skillet and cover until kale turns bright green and wilts, about 5 or 6 minutes. Remove lid, add water and cook until liquid is evaporated about 10 minutes. Add bacon pieces and toss with vinegar, salt and pepper.