Step 1

Season both sides of steak with salt and pepper. Heat oil in a skillet over medium-high heat. Cook steak, turning occasionally, to medium doneness, about 6 minutes per side. An instant-read thermometer inserted into the center should read 135 to 140 degrees F (60 degrees C). Transfer meat to a bowl to let it rest.

Step 2

Pour a splash of water into the skillet; stir to scrape up browned bits and deglaze the pan. Pour this liquid over meat. Allow meat to cool completely.

Step 3

When meat is completely cool slice thickly (about 1/2 inch) with the grain, then cut into thinner strips. Dice by cutting into pieces against the grain. Transfer chopped steak back to the bowl; toss with the pan drippings.

Step 4

Melt bacon fat over medium heat in a pot. Add onions and a pinch of the salt; cook and stir until softened, 5 or 6 minutes. Stir in oregano. Add pinto beans and water. Bring back to a simmer and cook until onions are soft and sweet, about 5 minutes. Reduce heat to low.

Step 5

Mash the beans with a potato masher to your desired consistency. Add additional liquid, if necessary, to achieve your preferred texture. Add the remaining salt to taste. Remove from heat.

Step 6

Preheat oven to 450 degrees F (230 degrees C).

Step 7

Place tortilla chips about 2 or 3 deep in a heat proof pan. (You may need more than one pan.) Top chips with spoonfuls of beans and a generous handful of steak pieces. Sprinkle with grated cheese.

Step 8

Bake in preheated oven until cheese is melted and edges start to brown, about 10 minutes.

Step 9

Scatter diced ripe avocado, diced onions, diced tomatoes, and diced jalapenos over the top. Drizzle nachos with sour cream and garnish with chopped cilantro.