Step one: pound out duck or goose breast flat with tenderizing meat mallet
Step two: marinate in Italian dressing with mustard around 2/3 to 3/4 dressing 1/3 to 1/4 mustard plain old cheap yellow mustard is what I use. I marinate mine in a zip lock large enough to hold the amount of meat I'm making and enough marinade to cover all the meat.
Step three: I always let mine marinate over night then cook the next day on the grill or cast iron pan with some bacon grease or butter medium rare if cooked all the way through it's not nearly as good. I can't stress that enough medium rare not medium well or medium. MEDIUM RARE! If you want to feed someone else this no matter what they say, and how much they like steak well done it's best MEDIUM RARE. Duck, goose, and deer a like gets to dry, tough, and livery tasting if it doesn't have some red in the middle.
This is one of my favorite ways to enjoy duck or goose. I have eaten canadians this way and many ducks. Never done it with divers or snow geese though. I always fry my divers and make snows into burger or jerky. I made this one time with my girlfriend told her I was cooking her steak, didn't say from what animal. She ate it no problems asked how I cooked it cause she liked it but was a little different than most steak, that's when I told her it was goose. She now has no problems trying anything I make with wild game.