Preserved Lemons Ingredients 4 cups extra-virgin olive oil 12 lemons, washed and dried 3 whole peeled garlic cloves 6 whole black peppercorns (roughly 1/4 tsp) 1 whole star anise 6 thyme sprigs 1 rosemary sprig Preparation Place the ingredients in a slow-cooker. Cover and cook on low for 10 hours, or until the lemons are very soft. The lemons are ready to use immediately; store the lemons and strained oil in separate containers. Notes The lemons can be stored in the refrigerator for up to a month; keep the oil stored in a separate container in the fridge, for lemon-flavored oil wherever olive oil could be used, and you want that lemon essence.