Thinly slice your onion and julienne the carrots. Put aside.
In a large skillet, pour your oil and heat to medium high heat. Sautee onions until translucent and slightly golden and then add carrots.
Pour in 1 c of stock or dashi and cover. Let cook 3-5 minutes until carrots soften.
Pour soy sauce, mirin, and stock into a large bowl and mix. Put aside.
Remove vegetables and put side. Put beef into pan and cook until mostly browned.
Add vegetables back, then pour in the sauce mixture. Bring to a simmer and simmer for 5 minutes, or until meat is cooked through.
Serve with rice and enjoy!