How to Make It
On a large plate, coat the salmon fillets with the miso. Wrap the fillets in plastic and refrigerate overnight.
Fill a large bowl with ice water. Cook the asparagus in a skillet of salted boiling water until crisp-tender, about 3 minutes. Transfer the asparagus to the ice bath to cool, then drain and pat dry.
In a small saucepan, heat 1 tablespoon of the olive oil. Add the shallot and cook over moderate heat, stirring, until softened, about 2 minutes. Add the black garlic and fish stock and cook over moderate heat until the stock is reduced to 1/3 cup, 7 to 8 minutes. Stir in the cream and cook over moderately low heat, stirring occasionally, until the sauce is thickened, about 10 minutes. Transfer the sauce to a blender and puree until smooth, then strain through a fine sieve set over a small saucepan, pressing on the solids. Season with salt and pepper and keep warm.
Wipe the miso off of the salmon fillets and rinse them; pat thoroughly dry. In a large nonstick skillet, heat 2 tablespoons of the olive oil. Cook the salmon skin side down over moderate heat until the skin is golden brown and crisp, 3 to 4 minutes. Turn the fillets and cook over moderately low heat until just opaque throughout, 3 to 4 minutes longer. Transfer the salmon to a plate to drain briefly.
Wipe out the skillet and add the remaining 1 tablespoon of olive oil. Add the asparagus, season with salt and pepper and cook over moderate heat, stirring, until warmed through, 2 minutes. Transfer the asparagus to plates. Top with the salmon fillets and drizzle with some of the black garlic sauce. Serve the remaining sauce on the side.
Black garlic is prized for its sweet and savory, deep molasses-like flavor; its jelly-like texture makes it perfect for adding to sauces because it dissolves so easily. It’s available at specialty shops and from blackgarlic.com.