Heat grill to high. Brush the fennel with olive oil and season with salt and pepper, to taste. Grill for 3 to 4 minutes per side or until slightly charred and almost cooked through. Place fennel on a platter and scatter orange segments over the top. Whisk together the orange juice, zest, mustard, and olive oil in a small bowl. Season with salt and pepper, to taste. Drizzle vinaigrette over the salad. Sprinkle with almonds and mint and serve.