Tonkatsu is breaded deep-fried pork. You don't need special ingredients to make tonkatsu, so it's easy for everyone to cook it at home.
Ton means pork in Japanese. If you use chicken for this dish, it's called chicken-katsu. You can also use beef and make beef-katsu. Also, menchi-katsu is a fried meat cake.
Tonkatsu sauce can be purchased at supermarkets or online stores. If it's not available, mix any steak sauce or Worcester sauce with some ketchup. Usually lot of thinly sliced cabbage is served with tonkatsu. It's important to soak cabbage slices in cold water. Then, drain well before serving. Also, lemon and karashi(Japanese mustard) usually accompany tonkatsu. Squeeze some lemon over tonkatsu and dip some karachi as you eat.
Tonkatsu itself can be arranged into other dishes. The most famous is katsu-don. Simmered tonkatsu is served on top of steamed rice. Other one is katsu-curry. Tonkatsu is served on top of rice with curry sauce.
Enjoy!
