Step 1

Cook oil and achiote seeds in a small saucepan over medium-low heat until oil turns deep orange, about 10 minutes. Strain into a heatproof jar and let cool. Measure out ½ cup achiote oil for making filling; set remaining 1 cup oil aside for making dough.

Step 2

Bring beef, chicken, 1 Tbsp. Diamond Crystal or 1¾ tsp. Morton kosher salt, and 12 cups water to a boil in a large pot over medium-high heat. Reduce heat to medium-low and let simmer until cooked through, about 30 minutes. Transfer beef and chicken to a cutting board and let sit until cool enough to handle. Pour 8 cups cooking liquid into a heatproof pitcher or large measuring glass; set aside. Discard any extra liquid.

Step 3

Cut beef and chicken into ⅓" cubes; place back into pot (cooking the meat before you chop it means that you can cut the pieces finer and more evenly). Blend tomatoes, garlic, and tomato paste in a blender until smooth; scrape purée into pot with meat. Blend onion, red and green bell peppers, scallions, cilantro, and ½ cup reserved cooking liquid in blender until smooth and add to pot. Add brown sugar and ½ cup reserved achiote oil. Pour in remaining 7½ cups reserved cooking liquid. Bring to a boil, then reduce heat to medium-low and simmer until meat is tender and liquid is slightly reduced, about 40 minutes. Drain meat in a colander, season lightly with salt, and let cool.

Step 4

Meanwhile, mix cornmeal, salt, reserved 1 cup achiote oil, and 8 cups water in a large bowl with your hands until dough is smooth, spreadable, and no large lumps remain, 5–7 minutes. Press a sheet of plastic wrap or parchment paper directly onto surface of dough; let rest at least 30 minutes or up to 1 hour.

Step 5

Wash and pat banana leaves dry. Carefully remove any center stems with kitchen shears, avoiding breaking through the leaf, then cut into 14x10" rectangles. Mix oil and 1 cup water in a medium bowl (it needs to be big enough to dip your hands into). This will help to keep the dough from sticking to your hands. Working one at a time, place a banana leaf on a surface so the veins in the leaves run horizontally. Dipping your hands in oil mixture as you work, place ¾ cup dough in center of leaf and spread out with your fingers into a ⅛"-thick rectangle, leaving a 1" border near the vertical edges and a space on both horizontal edges. Place ¾ cup guiso into center of dough. Top with 5 capers, 2 olives, and 8 raisins.

Step 6

Take top and bottom edges of leaf and bring up toward each other so edges of dough meet and enclose filling. Pull both sides of banana leaf together snugly toward the upper edge of hallaca to seal and fold over toward you to make a tube. Fold remaining 2 side ends toward the center to make a small package.

Step 7

Place package, fold side down, on another banana leaf and wrap up again. Wrap once more in a third leaf to hold everything together, then tie closed with kitchen twine. (Make sure package is compact, the leaves are not ripped, and hallaca is not leaking.) Repeat with remaining dough, filling, and banana leaves.

Step 8

Place as many hallacas as will fit into a clean large pot, pour in water to cover, and bring to a boil. Reduce heat and simmer, turning hallacas halfway through, until plumped and firm, about 35 minutes. Repeat with remaining hallacas.Do ahead: Hallacas can be made 1 week ahead. Let cool, then cover and chill, or freeze up to 3 months. To reheat, cook in a pot of simmering water (make sure hallacas are submerged), partially covered, until warmed through, 10–15 minutes if chilled, 25–30 minutes if frozen.