The expression nose-to-tail dining is often associated with Fergus Henderson, who has been championing the eating of as much of an animal as is possible since 1994, when he opened his restaurant St John in London. But the practice of using the parts many discard is not new. In medieval Britain, brawn, a jellied cold meat made from pig's head was popular, and a favoured dish of the Romans was a sausage of pig offal enclosed in caul (fat found around organs).
In many Asian cuisines, including Cantonese, offal, heads and feet have long been part of the culinary repertoire. But Henderson's revival did spawn a trend that saw restaurants opening up in many countries following his lead. Western restaurants in Hong Kong have been slow to take up the movement. Two that have are Wild Grass and The Salted Pig. 
Wild Grass' organic, sustainable philosophy is evident the moment you walk into the large, naturally bright, country cottage-style restaurant, with its mismatched furniture (that appears to be second-hand) and repurposed timber.
Both the lunch and dinner menus offer dishes that fit within the nose-to-tail concept. We order a starter of sautéed kidney with bacon in a whole roasted pumpkin, and a main of baked lamb haggis with neeps (yellow turnip, also called swede) and tatties (potato).
The starter is appealingly presented with the kidney in rich, deep, earthy gravy inside a small pumpkin topped with melted cheese, and a sprinkle of flat leaf parsley.
The slices of kidney are cooked perfectly, with bacon and onion enhancing the taste. The pumpkin is more of vehicle than a flavour component, although it does contrast with the rich gravy, which is the star of the dish. A hiccup comes halfway through, when a small piece of clear, sharp, hard plastic is discovered in the gravy.
The server, clearly embarrassed, apologises profusely and returns the dish (and the plastic) to the kitchen. A replacement is hastily served. We think it unprofessional that the manager and the chef/owner didn't acknowledge the incident. That said, the dish is extremely satisfying.
Not so the haggis, however. Tasting of little more than pepper, with no bite, served on top of an overly mashed potato and yellow turnip with a puréed texture, it is disappointing. It has a mushy texture, reminiscent of baby food.
Further investigation reveals the chef is unable to source two key ingredients of haggis: sheep's lung and heart. The haggis at Wild Grass contains only the third offal ingredient, liver, with the addition of kidney. Calling it haggis seems misleading.
Also going for a rustic look with its stylised farmhouse interior, is The Salted Pig. It has painted wooden chairs, wood-topped tables, a distressed paint finish, a cement floor and decorative objets including hessian sacks and enamelled tinware. There is an overwhelming smell of popcorn on entering, which seems to be served instead of bread.
Cuts used by the restaurant include pig's cheek, neck, shoulder, rump, trotters, tenderloin, shank, leg, and belly, and chicken livers. The first three, plus the chicken liver, are the core components of the home-made terrine of pork with pistachio wrapped in bacon and baked. It is served with piccalilli (spicy pickled vegetables), crusty bread, and dressed flat-leaf parsley.
Porky and peppery, the pickles add balance. The dish is pleasant but lacks the wow factor.
A half-rack of barbecue ribs with fries follows, but the home-made smoked barbecue sauce is too salty and peppery for our taste. Even the fries have pepper on them, which seems a bit odd. The three meaty ribs are tender, but the flavour is overwhelmed by the sauce.
Wild Grass scores high marks for offering more unusual parts of an animal (oxtail, tripe, and tongue also currently feature), and the starter is excellent. But there is the main course to consider. No dish at The Salted Pig is offensive, but none is superb. So it is a tie.
Wild Grass, 1/F, 4-8 Arbuthnot Rd, Central, tel: 2810 1189, wildgrass.hk 
The Salted Pig, 2/F The L Place, 139 Queen's Rd, Central, tel: 2870 2323, thesaltedpig.com.hk