Submerge fennel in small pot with 1 cup orange juice. Season with salt. Cover pot and cook over medium high flame until tender, about 5 to 10 minutes.
In a small kettle mix chopped mango, sugar, remaining 1 cup orange juice, lime juice, cinnamon, nutmeg, salt and hot red pepper sauce. Heat rapidly, and then reduce to a simmer. Cook for about 20 to 30 minutes.
Season tuna, to taste, with salt and pepper. Add oil to skillet and preheat over medium flame. Sear both sides of tuna. Cook until tuna is about medium done. Remove from heat and slice into 8 slices.
Grill or toast baguette bread. Spread 1 side of each slice with spicy mango molasses.
Arrange seared tuna and braised wild fennel on top of the bread.
Glaze the top of the sandwich with mango molasses.
Recipe courtesy of Daniel's Head Village, Sands Parish, Bermuda