Just around the corner from Rue Cler is one of the best small epicerie shops in Paris, where you can buy olive oils, vinegars, teas, coffee, spices, high-quality canned tuna, chocolates and other specialty items. The owner is very friendly and helpful, as are his staff. Whenever we want something special (most recently brown sugar, which is not sold in grocery stores), we come here.
Given their large variety, this is the go-to place for some of those harder to find items. One year for Thanskgiving I came here to buy chestnuts for stuffing and another time, for a dinner party, I bought black truffles. You can even buy traditional foie gras (if in stock). All items are reasonably priced.