Pepper Crusted Seared Ahi Tuna with Tahini Sauce

Name: Pepper Crusted Seared Ahi Tuna with Tahini Sauce
Ingredients: For the Tuna:; A thick piece of sushi grade Ahi tuna (about 1 lb) or 2 smaller pieces; 1/2 tablespoon whole black peppercorns; 1/2 tablespoon butter; 1/2 tablespoon canola oil; 1/2 teaspoon Piment D’Espelette (or hot paprika, or a pinch of cayenne); kosher salt; freshly ground black pepper; For the Tahini Sauce:; 1/2 cup water; 1/4 cup tahini; 2 tablespoons champagne vinegar (or white wine vinegar); 2 tablespoons fresh Meyer lemon juice (or regular lemon); 1 to 2 teaspoons honey; 1 tablespoon dijon mustard; 1 garlic clove, minced; 1/2 teaspoon salt; freshly ground black pepper to taste