You can use any cut of beef but I prefer flank, round, or brisket for this dish.
Cut the beef into 2x3 inch blocks with the grain following the long side.
Place beef, onion, radish, and garlic into a pressure cooker/instant pot and cook under manual high pressure for 10 minutes. Let pressure release naturally.
Drain through a fine-meshed sieve lined with cheesecloth and reserve broth.
After rinsing out the instant pot, place 2 cups broth back into the pot.
Add the cooked meat, peppers, soy sauce, sugar/syrup, and mirin to the instant pot.
Cook under manual high pressure for 10 minutes and let pressure release naturally.
Slice meat against the grain and serve with peppers.