Halloumi is the grilling cheese of Cyprus, and a protected name. The curd is heated, so a slab stays in one piece on a hot pan instead of melting into a puddle.
The protected name covers halloumi and hellim, the Greek and Turkish names of the Cypriot cheese. Traditional halloumi is sheep and goat milk. Much of the cheese now includes cow's milk. It is salty from the brine, and mint is a traditional flavor.
History
Cyprus has made a firm brined cheese for a long time, in a mixed Greek and Turkish culinary island. Hellim and halloumi are the two names of that cheese. Heating the curd was the practical discovery that matters. A cheese that can be fried for breakfast, without running off the plate, fits a cuisine that cooks in a pan and eats the cheese hot.
The cheese left the island as a specialty and then became a supermarket item in Britain and much of Europe, especially as a vegetarian grill. The protection ties the names halloumi and hellim to Cyprus. A grilling cheese made elsewhere in the same way is a halloumi-style cheese, even if a shop shortens the label. The island cheese is the reference.
How it is made
Milk is set and the curd is cut and pressed. The curd is then heated in hot whey. That heating changes the protein so the finished slab softens and browns in a pan but does not fully melt. The cheeses are salted in brine. Dried mint is often added. Sheep and goat milk are the traditional base. Cow's milk is now common in the mix, including in much of the cheese sold abroad.
The brine keeps the cheese salty and moist. A block that sits dry in a refrigerator will toughen. A block sold for grilling may be firmer than a very fresh Cypriot cheese eaten on the island. Both can cook. If a cheese melts away into a puddle, it was not heated in the make, whatever the front of the package said. The squeak when you bite a hot piece is part of this method.
Taste
Halloumi tastes salty and milky, with mint when mint was added. Cold, it can seem plain and firm. Hot, the outside is browned and savory and the center softens. Sheep and goat milk give a fuller flavor than a cow-heavy block, which is often milder and saltier and little else.
A good grilled piece is salty but not bitter, and the browning tastes toasted rather than burnt. A block that smells sour in the brine, or that feels chalky and dry, has been kept badly. Rinse a very salty piece before cooking if the rest of the meal is already seasoned. Do not rinse it into tastelessness. The salt is normal.
In the kitchen
Dry the slab and fry or grill it until both faces are brown. Eat it hot, with lemon, salad, flatbread, or grilled vegetables. It is a breakfast cheese in Cyprus and a main-dish cheese in many vegetarian kitchens elsewhere. Cubes can go into a warm salad. It can be fried in a little oil without a batter.
Do not expect it to stretch like mozzarella, and do not expect it to crumble like feta. If it melts into the pan, you have a different cheese. Paneer is the substitute when you need a cheese that stays in cubes in a simmered sauce. Feta is the substitute when you need a salty crumble and do not plan to fry it. A grilling cheese from another country, honestly labeled, is the substitute when Cypriot halloumi is unavailable.
Around the world
Cyprus is the home, and both communities on the island claim the cheese under their own name. The protection recognizes that double naming. Britain became one of the large export markets, and from there the grilled slice entered pub menus, supermarket grills, and weeknight cooking across Europe and beyond.
Much of what is grilled outside Cyprus is made for that market and may contain more cow's milk than a traditional wheel. It can still be a satisfying grill. If you want the Cypriot cheese, look for the island and for the protected name. If you want any firm salty slab that browns, a style cheese will do the cooking. Mint, brine, and the refusal to melt are the three clues that the method is right.