In a bowl, combine wine and mustard to dissolve. Add ginger, garlic, oil and juniper berries. Coat squab with marinade and let stand for 4 hours. Season the squab. Heat a skillet and coat with oil. Pan sear the squab, breast side down until brown, about 3 to 4 minutes. Flip and cook an additional 3 to 4 minutes. Squab should be eaten rare. Let rest 4 minutes.
WATERCRESS SALAD: In a bowl, whisk together juice, sugar and oil. Toss well with nuts and greens. Season and check.;
MANGO SAUCE: In a small stockpot or large saucepan, coat lightly with oil and brown mire poix. Deglaze with wine and reduce by 80 percent. Add thyme, ginger, pepper, soy, carcasses and cover with water, (6 to 8 cups). Bring to a boil and turn down heat to simmer, 11/2 hours. Strain. Place in another saucepan and reduce by 50 percent. Whisk in the mango puree and butter. Season and check. Keep warm.
PLATING: On white plates, sauce the whole plate. Place a small mound of salad in the center and lay 2 pieces of squab on top, legs crissed-crossed. Garnish with nuts.