Spicy Sesame Vinaigrette: Whisk together olive oil, vinegar, tahini and soy sauce until blended. Stir in ginger, sugar, garlic and sriracha. Set aside.

Tuna Salad:

• Coat tuna with 1 tbsp olive oil; sprinkle with salt and pepper. Heat remaining olive oil in large heavy-bottomed skillet set over high heat until shimmering; cook tuna for 30 to 60 seconds per side or until seared on the outside but rare on the inside. Let tuna rest for 5 minutes before slicing across the grain.
• In large bowl, combine lettuce, cucumber, red pepper, celery and green onions; toss with vinaigrette. Divide salad among 4 plates; top with kimchee and sliced tuna. Garnish with sesame seeds.