Set oven to 350F.
Spray slices of sourdough with avocado (or olive) oil, then sprinkle with sea salt & pepper. Toast in the oven for abut 5 minutes, until golden brown and crunchy, almost like croutons. Let them cool to harden, then cut in to small squares. Set aside.
In a large bowl, whisk together eggs and coconut milk. Set aside.
Set a nonstick skillet on medium-high heat. Once hot, lightly spray with oil, then toss in the chopped steak. As it begins to cook, sprinkle in sea salt, pepper and thyme. Sear and cook until your desired readiness, about 4 to 6 minutes. When the steak is almost to your satisfaction, toss in onion and optional mushrooms. Continue cooking and searing for the remaining time.
Spray a large muffin mold with oil. To each muffin tin, equally divide the meat & onion mix, toasted sourdough and bell pepper. Pour in the beaten eggs and fill about 2/3 of the way up. If desired, top with cheese.
Bake for 20-25 minutes, or until the egg is cooked through. Enjoy!