Many modern recipes call for coarse salt or coarse sea salt and various brands are readily available in stores and supermarkets. A reference to “coarse salt” in a recipe means what in the USA is generally referred to as kosher salt. There is nothing actually “kosher” about the salt itself. The reference is to the fact that the particular shape of the grain of coarse salt makes it the best option for drawing the blood out of meat, which is a requirement of Jewish law, and therefore it is an important part of the process of making meat kosher.
Furthermore, coarse salt is neither saltier nor more flavoursome than ordinary table salt, but again, because of the coarser, larger shape of the grain, it has more of a dramatic effect on the taste buds than ordinary salt, so it seems to be saltier and stronger.
This makes it not very good for baking (which requires a finer grain for a better dispersal) but excellent for sprinkling on foods to which you wish to add a contrast, such as salted caramel and sweet desserts, bread, or steak. And because a little goes a long way, we are inclined to use less of it, which is healthier.
For exactly the same reason as why coarse salt is used in preparing kosher meat, so it is also excellent for helping to achieve a good crackling on a pork joint. The coarse salt, rubbed into the skin and left overnight will draw out the water far more effectively than ordinary fine grain table salt, precisely because the crystals will stick better to the surface.
Kosher salt may be either salt mined from the land or evaporated from the sea. Coarse ‘land’ salt is made by compressing the grains into irregular sized platelets or flakes. Coarse sea sold achieves a similar result but by a process of evaporation of seawater. Different seawaters containing different minerals give sea salt a wide variety of subtly different flavours and colours, the colours ranging through white, pink, and black. These subtle flavours are lost in cooking, so sea salt is best used as a garnish or sprinkle.