Green beans with mustard butter sauce is a quick and easy side dish with only 5 ingredients!
Cook green beans in boiling, salted water until crisp-tender, about 5 minutes.
In the meantime, combine the remaining ingredients in a medium bowl and stir to combine.
Drain the green beans, then add to the bowl and toss with the mustard sauce to coat. Serve immediately.
You can substitute olive oil for the butter if you’re vegan or if you want the sauce to be more of a vinaigrette.
I like the texture and flavor of the whole grain mustard, but if you don’t have any, you can use all Dijon mustard here.