Make the marinated onions first by adding onions, olive oil, red wine vinegar, thyme, oregano and salt and pepper to a bowl. Toss to combine and let sit while you make the rest of the recipe.
Add southwest seasoning to steaks and season with salt & pepper to taste, then set aside while you prep the lettuce, cherry tomatoes and grate the cheese.
Add a bit of olive oil to a skillet, then add corn. Season with salt & pepper, sauteeing over medium-high heat for 3-4 minutes until charred. Remove from heat and set aside.
Heat olive oil in a large skillet over medium-high heat, then add steaks, cooking for 2 to 3 minutes per side depending on the thickness of your steak. Alternatively, you can grill the steaks on a BBQ. Once cooked, remove from heat and let rest for 5-10 minutes before slicing up.
While steak cooks, make the dressing by blending cilantro, lime juice, olive oil, garlic, cumin and salt & pepper in a Magic bullet or individual-sized blender.
Divide sliced steak, lettuce, cherry tomatoes, charred corn, black beans, chopped avocado, grated cheese, marinated onions and tortilla strips among 4 bowls. Pour dressing overtop, then serve and enjoy!