Easy tasty sauce for steak

Make a Chimichurri

Best steak "sauce" IMO

Juice from another steak would make a great sauce

The secret is minced garlic and a little bit of soy. That's it. The secret family recipe.

Horseradish, garlic, sour cream, and squeeze of lemon for a tangy cream sauce.

Personally I just throw some garlic/herb butter into the skillet with the steak and make a quick pan sauce to drizzle over it

Either a béarnaise or bordelaise would be good with both shrimp and steak.

Butter, thyme, rosemary, with sautéed garlic and maybe a little squeeze of lemon/ lemon zest would do the trick too, this is essentially just a dressed up bordelaise though. Add mushrooms or onions if you want to as well, just don't burn the garlic.

My favorite way to top a steak is with red onion medallions topped with blue cheese crumbles until the onions are cooked and the cheese has browned on top. You can do this with a grill or in your oven. It can be a little tricky keeping the onions in whole medallions on the grill though, coat lightly with olive oil to keep them from sticking.