Take steaks out of fridge 30 minutes prior to cooking them.
Pre-heat oven to 350F to warm tortillas. Wrap tortillas in foil and place in oven.
Make the pico de gallo by slicing the tomatoes, removing the seeds, and then chopping them into smaller pieces. Chop the onion, cilantro, and serrano pepper. Add lime juice and salt and pepper and mix together. Set aside.
Slice avocado into desired size pieces and set aside.
Season both sides of the steaks generously with salt and pepper.
For the steaks, place a heavy pan on the stove on medium-high heat. I use my cast iron skillet. I like to get the pan really hot so let it heat for several minutes (I have an electric stove). Alternatively, you could grill the steaks if you prefer.
While the pan is warming up, add butter and mince garlic into a small pan on medium heat. The garlic will cook a bit to take the sharp edge off.
Once the steak pan is hot, add about two tablespoons of olive oil. Add the steaks and cook to desired doneness. It shouldn't take long... less than a minute per side.
Once steaks are done, drizzle the garlic butter on them. Let them rest for a couple of minutes and then slice them.
Serve tacos with pico de gallo, sour cream, and sliced avocado.