Combine the garlic, ginger, scallions, honey, soy sauce, grapeseed oil and vinegar in a mixing bowl. Marinate the fish fillets in this mixture for at least 2 hours, preferably overnight, refrigerated.
Transfer the cod and marinade to a shallow pan and slowly poach the fish over low heat until it is fork tender, 10 to 20 minutes.
Slice the baguette into 18 pieces and lay out on a baking sheet. Brush with olive oil.
Preheat oven to 450 degrees F. Remove fish to a utility platter and flake. Transfer flaked cod to a strainer set over a bowl to drain excess moisture. Discard this excess liquid and put the flaked cod into the bowl.
In another small bowl, combine mayonnaise, scallions and relish to make a tartar sauce. Gently fold this tartar sauce into the flaked fish to help bind it.
Put the cod on the crouton and place in oven until the fish has a golden brown hue. Remove from oven and garnish with each appetizer with 1/8 teaspoon caviar and a small amount of parsley before serving.