Part of what can make a kidney taste strong is the uric acid in it.
For this reason, kidney is often soaked soak for an hour before using in something acidic, such as buttermilk or water with some vinegar or lemon juice in it, or just plain milk.
Despite the presence of uric acid, the kidney should not smell of urine — if it does, return it to the store.
Beef kidney looks different from lamb or pig kidney. Those two are all one organ; beef kidney is one central piece of flesh surrounded by little pieces. Beef kidney can be separated into its smaller lobes if you wish.
Beef kidney is tougher than veal or lamb kidney; it will need a different cooking method from them.
Trim off any fat and membrane with scissors or sharp knife (your butcher may have already removed the membrane.)