Swedish cuisine could be described as centered around cultured dairy products, crisp and soft (often sugared) breads, berries and stone fruits, beef, chicken, lamb, pork, eggs, and seafood. Potatoes are often served as a side dish, often boiled. There are a huge variety of breads of different shapes and sizes, made of rye, wheat, oat, white, dark, sourdough, and whole grain, and including flatbreads and crispbreads. Many meat dishes, especially meatballs, are served with lingonberry jam. Fruit soups with high viscosity, like rose hip soup and blueberry soup (blåbärssoppa) served hot or cold, are typical of Swedish cuisine. Butter and margarine are the primary fat sources, although olive oil is becoming more popular. Sweden's pastry tradition features a variety of yeast buns, cookies, biscuits and cakes.