Heat the oil in a wide pot or deep skillet over medium-high. Add the beef and sear just until it loses its raw color, about 1 minute. Lift it out and set aside.
Add the onion wedges and potato chunks to the same pot. Stir for 2 minutes to coat them in the beefy oil.
Pour in the dashi, soy sauce, mirin, sake, and brown sugar. Bring to a gentle simmer and skim off any foam.
Add the carrot and the shirataki if using. Lay a drop lid or a loose lid on top and simmer for 15 to 18 minutes, until the potatoes are fork-tender.
Return the beef to the pot and simmer uncovered for 3 to 4 minutes, letting the broth reduce slightly.
Stir in the blanched snow peas, turn off the heat, and let it rest for 5 minutes so the flavors settle. Serve warm, over rice if you like.