Carrots with butter, onions and olive oil

my mothers recipe which mike like a whole lot.

1 lb carrots (cut the carrots 1/2 inch on the bias)
l tbsp butter
1/4 cup olive oil
1 medium onion
salt and pepper to taste

saute the onion, olive oil and butter until the onions become opaque.  put in the carrots and saute covered about 10 min turning about one time on a low/medium flame.