Poached Arctic Char with Basil-Tarragon Mayonnaise

Ingredients

• 1.5 pounds asparagus trimmed
• 2 large egg yolks 
• 0.3 cup basil leaves fresh
• 1  garlic clove smashed
• 2 tablespoons kosher salt plus more
• 2 tablespoons juice of lemon fresh
• 1 tablespoon ground mustard 
• 0.8 cup olive oil extra-virgin plus more for serving
• 6 servings flaky sea salt (such as Maldon)
• 36 ounce arctic char steaks thick
• 0.3 cup tarragon leaves plus 2 sprigs fresh

Equipment

• bowl
• frying pan
• pot
• blender

Directions

1. Blend egg yolks, lemon juice, and mustard powder in a blender.
2. Add basil and 1/4 cup tarragon. With machine running, drizzle in 3/4 cup oil; blend until smooth.
3. Transfer mayonnaise to a small bowl, cover, and chill.
4. Combine tarragon sprigs, garlic, 2 tablespoons kosher salt, and 6 cups water in a large deep, lidded skillet and bring to a boil.
5. Add fish, cover, and remove skillet from heat.
6. Let stand until fish is just opaque in the center, 6-8 minutes.
7. Meanwhile, cook asparagus in a large pot of boiling salted water until crisp-tender, about 3 minutes; drain
8. Serve fish with asparagus; top with mayonnaise, drizzle with some oil, and sprinkle with sea salt.
9. DO AHEAD: Mayonnaise can be made 2 days ahead. Keep chilled.