Start by marinating the steak. Place all ingredients in a large bowl or dish, then press steak into the marinade and flip to coat both sides. Cover with plastic wrap and place in the fridge for at least 2 hours up to 24 hours.
Next make the Chimichurri. Mix all ingredients in a food processor or blender except the red wine vinegar and olive oil. Process/blend until smooth. Transfer to a medium bowl and top with the red wine vinegar and olive oil. Mix until incorporated, set aside for later.
When ready to cook, remove the steak from the fridge to get to room temperature. Place butter and EVOO in a cast iron skillet over high heat. Then once melted, toss in the peppers and onions. Try not to move them around too much because you want them to get nice and charred on either side. This should take about 10 min, stirring/flipping the veggies only once.
While the veggies cook. Heat a grill over its highest heat. When ready, remove the steak from its marinade, drain any sauce left on and grill for 2 minutes on either side. After each side has been grilled for 2 minutes, place the steak on the high grill shelf or over a cooler place on the grill and close the lid for two minutes. After two minutes, remove the steak and place some aluminum foil over it for 5 minutes while it rests.
While the steak is resting, assemble the board. Toast some tortillas and place them on the board with some tortilla chips. Add a bowl of guac to the board with a few lime wedges. Then add a small cup of cheese to a small bowl and add to the board. Move the cast iron veggies carefully to the board on a heating pad, trying not to burn yourself. Then finally, slice the steak against the grain, place on the board and top with flaky sea salt and chimichurri.