Preheat oven to 400°F (200°C).

Prepare the butter mixture: In a food processor, combine softened butter, chopped onion, chili powder, crushed garlic, orange zest and juice, lime zest and juice, honey, cumin, and salt. Puree until smooth.

Loosen the chicken's breast and thigh skin.

Spread three-fourths of the butter mixture under the chicken's skin.

Rub the remaining butter mixture over the chicken.

Let the chicken stand for 30 minutes.

Prepare the vegetables: In a medium roasting pan, toss sliced poblano peppers, jalapeno, sliced onion, and olive oil. Season with salt and pepper.

Place the Dr Pepper can in the center of the roasting pan.

Stand the chicken upright on the can.

Roast in the preheated oven for 30 minutes, or until lightly browned.

Reduce oven temperature to 325°F (160°C).

Continue roasting the chicken for 45 minutes, or until an instant-read thermometer inserted in the inner thigh registers 155°F (68°C) and the vegetables are tender.

Let the chicken rest for 15 minutes before transferring to a carving board.

Discard the soda from the can.

Remove the meat and skin from the chicken and shred.

Add the shredded chicken and skin to the roasting pan with the vegetables. Toss to combine.

Cover with foil to keep warm.

Prepare the corn tortillas: Heat canola oil in a medium skillet until shimmering.

Add a corn tortilla to the skillet and cook over medium-high heat until pliable, about 20 seconds.

Fold the tortilla in half and fry, using tongs to prop it open and turning occasionally, until a crisp shell forms, about 1 to 2 minutes longer.

Transfer the fried tortilla to a paper towel-lined baking sheet.

Repeat with the remaining corn tortillas, adding more oil as needed.

Prepare the flour tortillas: Heat a large cast-iron griddle over medium heat.

Place 2 or 3 flour tortillas on the griddle.

Scatter cheese, black beans, and white onion on top of each tortilla.

Cook over medium heat until the cheese is melted, about 1 to 2 minutes.

Assemble the tacos: Working quickly, wrap a crispy corn tortilla in a flour tortilla, pressing gently to help it adhere.

Repeat with the remaining flour tortillas, cheese, beans, and white onion.

Prepare the lime cream: In a bowl, whisk sour cream with lime juice and salt to taste.

Fill the double-decker taco shells with the Dr Pepper chicken and vegetable mixture.

Serve with the lime cream, salsa, avocado, cilantro, and lime wedges.