In a bowl, combine the thin sliced beef chuck steak with kosher salt, smoked paprika, cumin, and chipotle chile powder. Toss to coat the beef evenly with the spices. Let it marinate for about 10-15 minutes to absorb the flavors.
Heat the olive oil in a skillet over medium-high heat. Once hot, add the seasoned beef to the skillet. Cook for about 3-4 minutes, stirring occasionally, until the beef is browned and cooked through. Remove it from the heat and set aside.
In the same skillet, add the sliced colored bell peppers. Sauté for about 2-3 minutes until they are tender but still have a bit of crunch. You can toss in a pinch of salt to enhance their flavor.
Preheat your oven to 350°F (175°C). Place the Athens mini fillo shells on a baking sheet. Fill each shell with a spoonful of the cooked beef, followed by a few pieces of sautéed bell peppers.
Bake the filled phyllo shells in the preheated oven for about 10-12 minutes or until the shells are golden brown and crispy.
Remove the phyllo bites from the oven and let them cool slightly. Top each bite with a dollop of guacamole, a sprinkle of crumbled cotija cheese, and a sprinkle of minced cilantro. Arrange them on a serving platter, and enjoy!
