Place all vinaigrette ingredients into a bowl, whisk together until well mixed; set aside
For the salad, place the fennel, oranges, vinaigrette, cayenne pepper and sugar into a medium bowl. Toss gently, then season with salt and pepper.
Season cod with blackened seasoning to taste. Heat olive oil in a skillet over medium-high heat. Add the fish and cook 3 to 5 minutes on each side until bronze in color and opaque throughout. On each of 6 plates, place a piece of cod. Top fish with one-sixth of the salad mixture. Garnish with chives and dill.