The tradition of dim sum restaurants in London. There are many restaurants across London serving dim sum, and most are building on traditions that started many years ago in Canton. This type of food was originally offered as a snack in roadside diners to accompany a cup of tea, but gradually these snacks became more sophisticated, resulting in the food we know today. Look outside the best of London's dim sum restaurants on weekend mornings and you might see queues forming. That is because it is traditional to enjoy this type of Chinese food in the morning. Don't worry, though, you can enjoy these tasty delicacies in the capital at any time of day.