European BBQ potato dinner

An interesting twist on sauce- we thought it tasted somewhere between orange chicken sauce and a tomato based BBQ sauce. I changed up the recipe into a quick dinner or side dish. You can add meat or not.
Make the sauce while you are cooking the potatoes.

In a hot skillet, fry
1 Tb butter
3 red potatoes, cut into thin slices
1/2 red onion, chopped
when the potatoes start to soften, push to one side and brown over med-hi heat
1/4-1/2 lb thinly sliced pork loin or chicken pieces
When the down side is brown (about 3 minutes),
sprinkle with salt and pepper then turn over and
sprinkle with salt and pepper again.
when browned on all sides, stir together into the potatoes and onions. Add
1 Tb dried or fresh rosemary, smashed in a mortar
Cover, reduce heat, stirring occasionally until the potatoes are done to your liking, I seasoned it with salt and pepper again.
I found the sauce too heavy and almost sweet so instead of adding it to the whole dish, I served it on the side as a condiment. You decide.

Sauce:
Mix together in a small jar:
1/2 c ketchup
1/2 c fresh orange juice (or 2 Tb concentrate, still frozen, just scooped out of the container)
1 Tb Worcestershire sauce
1 Tb sesame oil