Think classic French steak au poivre on steroids and you have Aux Poivres Spice Blend. Instead of just one peppercorn, the blend has five, plus fennel and coriander.
It makes a great pepper crust on tuna and salmon but can be used on roasts and directly in dishes as a seasoning as well. I find myself using it on all my meat cooking, even on my bacon for breakfast.
It is a coarser blend than most so it should be added a bit earlier in the recipe than standard ground pepper.
If you can't find all the various peppercorns in your area, just use the ones you can. You can replace it with a good-quality homemade cracked black pepper, butcher's style.