Preheat your oven to 400 degrees.
Allow the flank steak to reach room temperature on your counter for 20 minutes.
In a large frying pan, heat 2 tablespoons of achiote oil over medium-high heat. Sauté the onions, peppers, and garlic until soft.
Turn down the heat to medium-low, add the beans, culantro, salt, pepper, and cook for another 3–4 minutes.
In a small bowl, combine the granulated garlic, adobo, paprika, salt, pepper, and rub onto the flank steak.
Move the beans to the sides of the pan (scraping up any bits that may still be left over from the sauté). Turn the heat back to medium-high and pour 2 tablespoons of oil into the center of the pan.
Sear the steak on both sides for 3 minutes. Then place in the oven for another 2–3 minutes or until your desired doneness.
Let rest for five minutes, garnish with scallions, and serve hot.