Hakka people are migratory tribes of ethnic Han people originated from central China. Their ancestors exiled themselves from foreign rulers such as the Mongols during the Yuan Dynasty. Due to their late migration to the southern areas of China, they found that all of the best land had been settled long before. The Hakkas then were forced to settle in the sparsely settled hill country.

As a result, fresh produce was at a premium, forcing the Hakkas to heavily utilize dried and preserved ingredients, such as various kinds of fermented beancurd and much use of onion. Due to the hill country being far inland seafood is a rarity. Pork is by far the most favored meat of the Hakkas, with belly bacon being the preferred cut as it has alternating layers of fat and lean meat, providing an excellent texture.

Famous dishes in Hakka restaurants in Hong Kong include:

Salt baked chicken - supposed to be baked inside a heap of hot salt, but many restaurants simply cook in brine nowadays.
Duck stuffed with rice - a whole duck is de-boned while maintaining the shape of the bird, the cavities are filled with seasoned sticky rice.
Tofu soup in pot - the stuffed tofu cubes.
Beef ball soup - very simple clear broth with lettuce and beef balls.
Other traditional Hakka dishes include:

Fried pork with fermented beancurd: this is a popular Chinese New Year offering which involves two stages of cooking. As previously mentioned, fresh food was at a premium in Hakka areas, so the marinated pork was deep fried to remove the moisture in order to preserve it. When a meal of pork was desired, the fried pork was then stewed with water and wood's ear fungus. Think of it as a Hakka equivalent to canned soup.
Ngiong Tew Foo (stuffed tofu cube): various oddments including eggplants, chillies and bitter melon stuffed with fish paste, beancurd, beancurd skin, fish and meat balls among other ingredients, served in clear soup.
Kiu nyuk (sliced pork with preserved mustard green): Alternate pieces of pork and yam served in a dark sauce whose principal component is, of course, fermented beancurd.
Lui Cha or Pounded Tea : A consortment of tea leaves (usually green tea), peanuts, mint leaves, sesame seeds, mung beans and other herbs, which are pounded or ground into a fine powder which is mixed as a drink, or as a dietary brew to be taken with rice and other vegetarian side dishes such as greens, beancurds and pickled radish.
Hakka food also includes takes on other traditional Chinese dishes, just as other Chinese dialects do.