In a non-reactive pot, combine all brine ingredients. Stir over medium heat until sugar and salt dissolve. Remove from heat and chill. Brine may be refrigerated up to three days. Place duck breasts in a non-reactive bowl and pour chilled brine over. Allow to brine for 6 hours.
Pat duck dry, place in a freezer zip-lock bag and zip nearly closed. Feed the smoking gun’s tubing (we employ the polyscience smoking gun) into the bag and dose with apple smoke. Seal and refrigerate for fifteen minutes. Repeat smoking once.
Finish the smoked duck in a cast iron pan over medium-high heat until fat is rendered and duck has reached medium-rare (6-7 minutes on the skin side, turn and sauté for 3 minutes more). Remove duck from the pan and quickly chill (may be refrigerated up to two days).
To prepare the quinoa, film a heavy-bottomed saucepot over medium heat with one tablespoon of extra virgin olive oil. Add shallot, garlic and marjoram. Season with salt and freshly ground black pepper and stir occasionally until shallots have softened (2-3 minutes.). Add quinoa and continue to stir until toasted and fragrant (3-4 minutes). Add stock and bring to a boil. Reduce to a simmer and continue to cook until quinoa is just done (13-15 minutes). Fold in olives and pine nuts, season and reserve.
For the vinaigrette, add citrus juice to a non-reactive pot and reduce by half, over medium heat. Remove from heat to cool slightly. Add Champagne vinegar, cumin, zest, scallion and mustard. Whisk to combine and then slowly add olive oil while whisking to emulsify. Adjust seasoning to taste and reserve.
To plate, stir vinaigrette into quinoa and spoon onto small dishes. Top with a slice of smoked duck breast, slice of grilled eggplant and garnish with a drop of black truffle oil and a few flakes of Maldon salt to finish.