Cod Cakes with Tarragon Aioli

Ingredients

• 1 Pound Fresh Cod
• 1/4 Cup Chopped Onion
• 1/4 Cup Chopped Celery
• 1/4 Cup Buttery Crackers, crushed into crumbs
• 1 Egg, beaten
• 4 Tablespoons Butter, divided
• 1 Cup Mayonaisse
• 1/2 Lemon, juiced
• 1 1/2 Tablespoons Tarragon
• 3 Teaspoons Kosher Sea Salt Flakes, divided
• 2 Teaspoons Ground Black Peppercorns Dustless, divided
• 1 Teaspoon Olive Oil
• 1/2 Teaspoon Garlic Powder
• 1/4 Teaspoon Mustard Powder