Peel cucumber; cut in half lengthwise, seed, and thinly slice.
Trim and discard fennel bulb base. Trim stalks from bulb, discarding hard outside stalk. Cut bulb in half lengthwise, and cut crosswise into thin slices.
Stir together fennel, cucumber, 2 tablespoons shallots, 1/2 tablespoon garlic, chives, 1/2 cup rice wine vinegar, olive oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper; let stand at room temperature 1 hour.
Place a small skillet over medium-high heat until hot; add fennel seeds, and cook, stirring constantly, 1 1/2 minutes or until toasted. (Be careful not to burn seeds; they will become bitter.)
Remove from pan. Reduce heat to medium. Process seeds in a blender until ground; return to pan. Stir in 1/2 cup grapeseed oil. Remove from heat; cool to room temperature.
Whisk together fennel-infused oil, remaining tablespoon shallots, remaining 1/2 tablespoon garlic, remaining 1/4 cup vinegar, remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, and orange juice; set aside.
Sprinkle scallops with salt and pepper to taste. Heat 1 teaspoon olive oil in skillet over high heat until very hot. Add scallops, and cook 2 minutes. Turn, and cook 1 minute.
Arrange salad on individual plates; top each with a scallop. Whisk vinaigrette, and drizzle over salads. Garnish, if desired, and serve immediately.