Prepare, slice, and cook all the necessary ingredients for the recipe. Season the beef with oregano, salt, and pepper. Adjust the seasoning to your taste—you're the one eating it. Brush a little oil onto the meat using a kitchen brush.

Heat a grill, skillet, or griddle well, and sear the beef on both sides. Spread mayonnaise on both halves of the bread. Place the beef on the bottom half of the bread, then add the tomato slices, cooked green beans, and chili pepper. Top with the other half of the bread and cut in half if you like.

OPTIONAL: Slice onion into thin strips. Toss with a little oil, lemon juice, salt, and cilantro. I personally like to add this—after all, I'm the one eating it.