Set aside cooked shrimp.
In a large pot filled with well salted water (should taste like the ocean), blanch leeks until tender. Remove leeks and place in salted ice water. When cool, drain well on absorbent towels.
Whisk egg yolk, cardamom, coarse ground mustard, dill seeds, champagne vinegar and salt in a small bowl until ribbon-like and smooth. Add canola oil in a slow and steady stream to thicken to the consistency of heavy cream. Taste for seasoning. Dressing should be homogenized in texture, with some background heat and flavor of mustard and aroma of cardamom and dill.
Cut the cooked shrimp in half lengthwise, trim the leek using the center, (most tender and sweetest portion) into rectangles. Season both well with salt and pepper, arrange attractively on plate with microgreens, and drizzle with vinaigrette dressing.