Halloumi can become a little rubbery and tough if you don't know how to use it. There are a few things you can do to avoid this: - cut your slices of halloumi on the thicker side - very thin slices tend to become a little hard, rather than soft and squidgy, like thicker slices do. - don't overcook the halloumi - a couple of minutes on each side is all it needs! You still want it to be soft, not totally crispy. - eat the halloumi within 5 minutes or so of cooking it - if you leave it to cool, it will become a little more rubbery.