Combine avocado, lime juice, garlic, and sour cream in a blender or food processor and puree until smooth. Set aside.

Season skirt steak with salt and pepper. Heat a heavy-bottomed pan over medium-high heat for 1 minute. Add butter and swirl it to coat pan. Add steak and cook until medium-rare, 12-15 minutes or until internal temperature is at least 145 degrees F, flipping once. Transfer steak to cutting board and let it rest at least 3 minutes.

While steak is resting, add corn kernels to the same pan with steak drippings and cook over medium heat until color is bright and some kernels begin to brown, 2-3 minutes. Season with salt and pepper.

In a separate pan, heat pinto beans. Slice steak into bite-sized pieces.

Toss cooked brown rice with cilantro and divide among 4 bowls. Top with steak, corn, pinto beans, jalapeños, and cotija, and drizzle with avocado crema.