With that in mind, you can definitely assemble everything up to a day in advance with no worries. Toss the packet and the steak on a hot grill and you will be in really good shape!

To assemble the foil packet two days in advance, follow these steps:

Make the spice mix (you can do this weeks in advance).
Slice peppers and onions, season and wrap them in the foil packet.
Season the steak, cover it, and keep it in the fridge.
Grill when ready!

Avocado
Sour cream
Red salsa, green salsa or pico
Hot sauce
After seasoning the steak and vegetables, you might have some spice mix leftover. You can use it to sprinkle on the fajitas before serving or keep it in the pantry. The spice mix is great on tacos and keeps well for three months in an airtight container.

INGREDIENTS
Fajita Spice Mix:

1 teaspoon kosher salt
1/2 teaspoon black pepper
1/2 teaspoon garlic powder
1/2 teaspoon onion powder
1/2 teaspoon ground cumin
1/2 teaspoon chili powder