In a 9x13 inch baking dish season duck liberally with salt, pepper, 1 Tbs cumin, and 1 Tbs oil. Cover with plastic wrap and let sit at least 30 minutes, up to 2 hours.
Preheat the oven to 400 F.
Remove plastic wrap and transfer dish to oven. Cook until the skin begins to brown deeply 30-45 minutes. The time will vary based on the size of the duck pieces and domestic vs wild duck.
Add ¾ cup duck or chicken stock and the bay leaves and continue cooking until the liquid is reduced by half, about 20 minutes.
Remove the baking dish from the oven and let duck cool in the rendered fat and broth mixture, at least 15 minutes.
Once the duck is cool enough to handle remove skin and set aside. Then using your hands or two forks shred the duck meat. Discard the bones and cartilage and add meat back to the pan with the duck fat/stock mixture. Remove the bay leaves.
Take 2 Tbs of the duck fat from the pan and melt in large saucepan over medium-low heat.
Add onion, garlic, remaining 2 Tbs cumin, orange zest, ¼ cup orange juice, remaining ¼ cup stock to the saucepan.
Reduce heat to low and cook until the onions are translucent and all the liquid has reduced. Set aside.
In a large flat pan (cast iron works great) heat 2 Tbs of vegetable oil on high until shimmering.
Add the shredded duck meat and any remaining duck fat from the pan to the oil and cook until golden brown and crispy. Transfer to a paper towel-lined plate to drain.
Add the drained duck to the saucepan with the onion mixture and mix. Adjust with additional salt and lime juice as needed.
In a dry pan over low heat, add the reserved duck skin and cook until fully crisped and rendered. Let cool then break into irregular pieces.
Make the Cabbage Slaw
Add the shredded cabbage and chopped cilantro to a bowl.
Combine juice from 1 lime, mayonnaise, and salt and pepper in small bowl, then pour over cabbage and mix well
Make the Sauce
Combine ¼ c mayonnaise, juice from half and lime, and siracha to taste.
To Serve
Warm tortillas in a dry skillet or over flame of a gas burner.
Serve the duck mixture on tortillas, followed by slaw, crispy duck skin, sliced radishes and finish with a drizzle of the sauce.