Prepare the white asparagus as outlined in the recipe tender white asparagus.: The aroma is subtly sweet and green as you trim and cook them, and you want a tender but slightly firm texture so the spears hold together on the plate. Use visual cues, a pale glossy sheen and slight bend, to judge doneness. Overcooked asparagus becomes limp and watery, so test the thickest spear with a knife or taste a tip to avoid that. If they seem fibrous, peel a bit more from the lower stalk to reveal the tender core.
Split lengthwise in half and set aside.: When you split the warmed white asparagus lengthwise, you expose a soft, pale interior that will accept vinaigrette and seared scallops beautifully. The cut surfaces should look moist but not soggy, and they will pick up the dressing and caramelized juices. A common mistake is cutting too soon after cooking while they are steaming hot, which can cause the asparagus to lose structure, so let them rest briefly to firm up.
Clean the scallops by removing the side mussel from the tender meat, then slice them in half horizontally. Season with the sea salt, white pepper and lime juice.: The scent of fresh seafood is clean and slightly briny as you trim the small side muscle and halve the scallops . Seasoning with flake salt and freshly ground white pepper enhances their natural sweetness, while a touch of lime juice brightens and slightly firms the surface. Avoid leaving them in acid for too long, since overexposure can start to cook the scallops and change their texture.
Seared them rapidly over very high heat, so the scallops are seared on both sides but still medium in the middle. Set aside.: As you hit a hot pan you will hear a sharp sizzle, and the surface of the scallops should turn a deep golden brown, creating a fragrant crust while the interior remains tender and slightly translucent. This contrast is crucial for texture and flavor, and the Maillard reaction from the sear produces nutty, caramel notes. If the pan is not hot enough you will steam rather than sear, resulting in a pale, rubbery edge, so always preheat thoroughly and pat scallops dry to encourage browning.
In a bowl, combine the mustard, with the chopped shallots and garlic. In a steady stream and under constant stirring add the virgin olive oil and the vinegar alternatively, to achieve a well emulsified vinaigrette. Add the tomato dice and the tarragon leaves, and season to taste. Infuse the vinaigrette for at least 20 minutes before serving.: The vinaigrette develops a silky mouthfeel as you slowly whisk in the olive oil alternately with Xeres vinegar , and the aroma of chopped shallots and minced garlic becomes more rounded with time. The diced tomatoes add little bursts of juice and color, while the torn tarragon releases its fragrant anise notes. Letting the dressing rest for twenty minutes helps the flavors marry, but be careful not to over dilute it with excess tomato liquid, which can break the emulsion, so drain any excess before dressing the plate.
In a microwave, just lightly warm the white asparagus and then place them on to your serving dish.: Warming the white asparagus briefly helps them regain a gentle heat without losing structure, and the warmth makes them receptive to the vinaigrette. The surface should feel just warm to the touch and appear glossy. Avoid overheating, which can cause dryness and a loss of flavor, so short bursts at low power with a quick check work best.
Neatly arrange the warm scallops on top of the asparagus. With a spoon, remove the solid part of the vinaigrette and dress it lengthwise on to the scallops. Drizzle the dish with the liquid of the vinaigrette, decorate with the pea shoots and sprinkle cracked pepper from the mill.: The final assembly is about balance and rhythm, placing each caramelized scallop so it sits partly on the white asparagus to marry the flavors. Use a spoon to add the thicker vinaigrette components along the scallops so the tomato and shallot bits anchor each piece, then finish with a light drizzle of the remaining liquid for gloss. The contrast between warm solids and cool, bright dressing is delightful, and the fresh pea sprouts offer a crisp finish. A mistake to avoid is dousing everything with too much dressing which can drown the delicate flavors, so apply sparingly and taste as you go.