Preheat the broiler. Season the cod with salt and pepper. Heat a large skillet over medium-high heat. Add the almonds and sesame seeds and cook, tossing, until toasted, 3 to 4 minutes. Transfer to a blender and puree until finely ground; set the blender aside.
Heat 1 tablespoon olive oil in the same skillet over medium-high heat. Add the leek and cook, stirring, until just beginning to brown, 3 to 4 minutes. Add the wine and cook until slightly reduced, about 3 minutes. Add 2 cups water and bring to a simmer. Add the cod, reduce the heat to low, cover and cook until just cooked through, 7 to 9 minutes. Remove the cod to a plate.
Transfer the leek and 3/4 cup of the cooking liquid to the almond mixture in the blender and blend on high speed until smooth and thick. Add more cooking liquid as needed to loosen.
Meanwhile, arrange the cabbage on a baking sheet and broil, tossing occasionally, until tender and browned in spots, about 8 minutes. Transfer to a bowl and toss with 2 tablespoons olive oil and the pepperoncini brine. Season with salt and pepper.
Toss the cilantro, olives, pepperoncini and remaining 1 tablespoon olive oil in a small bowl. Divide the cod among plates. Top with the almond sauce and olive mixture. Serve with the cabbage.