Wash the banana leaves thoroughly and pass them carefully over a gas flame or briefly dip them in hot water to soften them. This makes the leaves flexible and prevents tearing during wrapping. Cut them into large rectangles suitable for wrapping individual tamales.

Heat the vegetable oil in a skillet over medium heat. Sauté the chopped onion until soft, then add the garlic, cumin, paprika, salt, and pepper. Stir in the cooked shredded chicken or pork and cook for several minutes until everything is well coated with the seasonings. Set aside to cool slightly.

In a large bowl, beat the lard or butter until light and fluffy. Gradually mix in the masa harina, chicken broth, ají amarillo paste, paprika, cumin, salt, and black pepper. Continue mixing until the dough becomes smooth, soft, and spreadable.

Lay a softened banana leaf flat on your work surface. Spread a generous scoop of masa in the center, then add a portion of the seasoned meat. Top with one black olive, a slice of hard-boiled egg, and optional peanuts or raisins. Fold the banana leaf over the filling, creating a secure packet, and tie it with kitchen twine.

Arrange the wrapped tamales upright in a large steamer basket. Steam them over gently boiling water for about 2 hours, checking occasionally to ensure the pot does not run out of water. The masa should become firm yet soft and fully cooked.

Carefully remove the steamed tamales from the steamer and let them rest for about 10 minutes before unwrapping. Resting allows the masa to firm up slightly while retaining its soft and moist texture. Gently open the banana leaves to reveal the fragrant tamales and serve them warm with fresh salsa criolla, lime wedges, or your favorite Peruvian sauce.