Put all ingredients in a bowl or a bag. Let sit overnight or at least 4 hours.
Juice of 1 orange + zest, Juice of 1 lemon + zest, Juice of 1 lime + zest, ¼ cup olive oil, 1 tablespoon maple syrup, 1 teaspoon smoked paprika, 1 teaspoon dried cumin, ½ teaspoon of red pepper flakes (or more to taste), ½ teaspoon kosher salt, 1 skirt steak
When ready to cook. Preheat grill. cook 3-4 minutes a side. Let sit for at least 10 minutes.
Slice and marvel at how tasty it is.
Notes
This marinade would work with other cuts, of course. I'm thinking the best would be flank or London broil.
I've made this with and without the maple syrup. I like the sweetness the maple syrup adds but if you want less sweet results, I'd skip. The citrus is enough without it.
One time I made this with 4 cuties instead of an orange because it's all I had. Worked just as well.