Melt butter in large cast iron skillet over medium heat.
Add onion and saute until tender.
Add garlic, thyme, salt & pepper and saute and additional minute.
Add cubed corned beef, potatoes, and beets.
Press down with spatula and continue cooking over medium heat until bottom becomes crispy brown, 7-10 minutes.
Flip entire mixture, adding additional butter if sticking to the pan, press down with spatula.
Continue cooking an additional 5-7 minutes until crispy brown.
Serve topped with poached eggs.