Place the oil in a small saucepan. Scrape the vanilla bean and add the scraped seeds, and the pod to the oil. Heat over low heat to infuse the oil with the vanilla, about 10 minutes. Remove from the heat and cool slightly.
Season the tuna with salt and pepper. Rub with oil. Place on a hot grill pan and sear on all sides, about 8 minutes. The outside should be seared, but the inside should be rare.
Remove tuna from the heat and slice into thin slices.
Blanch the snow peas in salted, boiling water. Shock in an ice bath. In a large bowl combine snow peas, radishes, tomatoes, chopped parsley and basil and mesclun lettuce.
Toss with some of the vanilla oil. Serve on a platter with the tuna slices around. Garnish with fresh herbs and drizzle with a little extra vanilla oil.
Yield: 6 servings