I have played around with deep fried and pan fried pork tenderloin and sirloin for a long time now. I actually prefer the sirloin due to the added fat, however, here is what we did to make the Tonkatsu (breaded pork cutlet) in the restaurant.
Kobe Restaurant Tonkatsu
1 untrimmed, peeled tenderloin (meaning, we leave the fat cap on, but remove the membrane)
flour for dusting
2 eggs, whipped and room temp.
1/4 cup lowfat milk
2 cups 50/50 fine panko (Japanese breadcrumbs)
1/2 cup flour
salt and pepper (I use black pepper at home, but, white pepper in the restaurant was used)
At home, I fry in high heat grapeseed oil, however for the restaurant, we used high heat fry oil blend.
1. the egg and milk should be whisked together, strained to remove any albumen clumps.
2. Tenderloin was sliced into 1/2" thick medallions.
3. The panko and 1/2 cup flour are blended and tossed to coat the panko with flour
4. Using a serrated meat mallet, each medallion was pounded in each side to achieve a 3/16" thickness. This worked much better than a jacquard or smooth mallet. Doing both sides left us with fork tender tenderloins while allowing some thickness.
5. Dust all tenderloins after pounding and let sit on rack in fridge for at least 15 minutes to cure flour.
6. Dip tenderloin when ordered, first into egg wash, then into panko. Set on rack to cure for 5 minutes.
7. Deep fry until golden in 350°F oil, it will be done when golden
8. Set on grate to drain