DIRECTIONS
Heat 1 TBSP. olive oil in a large saucepan over medium-low heat.
Add shallot and sauté until softened and translucent, 4 minutes.
Add tarragon and cook 1 more minute.
Stir in 2 TBSP lemon juice, white wine, 1/2 tsp. salt, and 1/4 tsp. pepper.
Cook until mixture begins to bubble.
Add half-and-half, and increase heat to medium to bring to a boil.
Then reduce heat to low, simmering until mixture thickens slightly, 5 minutes.
Remove from heat, stir in 1/2 TBSP. butter, and cover to keep warm.
Heat remaining 1 TBSP. olive oil and 1 TBSP. butter in a separate large saucepan over medium-high heat.
Add mushrooms and sauté until deep golden brown, 6 to 8 minutes.
Remove mushrooms and set aside in a heatproof bowl.
For tuna crust, mix bread crumbs, lemon zest and remaining 1/2 tsp. salt and 1/2 tsp. pepper together in a dish.
Pat mixture all over each tuna steak.
Wipe out saucepan and coat bottom with oil.
Heat over medium-high heat.
Add tuna steaks and sear until crusts are golden brown and centers are pink, about 4 minutes per side.
Toss cream sauce, mushrooms and noodles together.
Slice tuna and serve alongside pasta.