In a Dutch oven, heat 2 tablespoons of olive oil over medium heat. Add 1 diced onion, 2 minced garlic cloves, and 1 chopped tomato. Sauté for 5 minutes until translucent. Stir in 1 cup of cooked red beans, season with salt and pepper, and sauté for another 10 minutes. Blend until smooth and set aside.

In a medium skillet, heat another tablespoon of olive oil and sauté the remaining onion, garlic, and 1 diced green bell pepper until softened. Transfer this mixture to a blender, blend with 1 cup of water until smooth. In a stand mixer, combine 2 cups of masa harina, 1 teaspoon of salt, and 1 teaspoon of bouillon powder. Gradually add in the blended mixture until a soft dough forms.

To make the banana leaves pliable, immerse each square in boiling water for 30 seconds. Remove and pat dry.

On a piece of parchment paper, lay out a banana leaf. Scoop 2 tablespoons of masa dough onto the leaf, slightly flatten. Add about 2 teaspoons of filling in the center. Fold the edges over and secure with cooking twine. Repeat until all ingredients are used.

In a large Dutch oven, arrange a steaming rack. Place tamales upright and pour boiling water until just below them. Cover and steam for 1.5 hours, checking water level to prevent burning.