Tostones Rellenos con Vaca Frita

Name: Tostones Rellenos con Vaca Frita
Ingredients: 2 ripe Hass avocados; 1/4 cup chopped cilantro, optional, plus more for serving; Juice of 1 lime; 1/2 teaspoon kosher salt, plus more for sprinkling; 1/2 teaspoon olive oil; 2 very green plantains (firm to the touch, no yellow spotting); 3 cups neutral oil, for frying; Vaca Frita, recipe follows; Lime wedges, to serve; 1 1/2 pounds flank steak, cut into 3 pieces; 3 bay leaves; Generous pinch plus 2 teaspoons kosher salt, plus more as needed; 5 cloves garlic, minced; 1/2 teaspoon ground black pepper; 7 tablespoons olive oil, or as needed; 1 1/2 yellow onions, thinly sliced; Juice of 3 to 4 limes