For the crab cakes: Combine the mayonnaise, Dijon mustard, stone-ground mustard and paprika in a large bowl. Add the crab, parsley and green onions and gently mix to combine. Begin adding the breadcrumbs 1/4 cup at a time until the mixture just holds together. Cover and refrigerate for at least 1 hour and up to 24 hours.
For the sour orange sauce: Combine the orange juice, lime juice, vinegar, chile powder, cumin and garlic in a medium saucepan, bring to a simmer over high heat and cook until reduced by half; season with salt and pepper. Strain into a bowl, add the honey, oregano and zest and let cool to room temperature before serving.
For the mango-avocado relish: Combine the avocado, mango and red pepper in a medium bowl. Toss with the cilantro, canola oil, lime juice and salt and pepper. Let sit at room temperature for 30 minutes before serving.
To finish the crab cakes, divide the crab mixture into 8 cakes and place on a parchment-lined baking sheet. Brush the tops of the cakes with mayonnaise and place overlapping layers of sliced plantains on top. Season the tops with salt, pepper and chile de arbol.
Heat 3 tablespoons of canola oil in a large nonstick saute pan over medium heat until the oil begins to shimmer. In batches, add the crab cakes plantain-side down and cook until golden brown, about 5 minutes. Flip and continue cooking until just heated through, about 5 minutes longer. Repeat with the remaining crab cakes, adding up to 3 tablespoons more oil if needed.
To serve, spoon some of the sour orange sauce into the bottom of 4 shallow bowls. Top with 2 crab cakes followed by some mango-avocado relish. Garnish with cilantro leaves.