In a small bowl, whisk together the vinegar and wasabi powder until dissolved. Mixture will be slightly green. Add the shallot and whisk to combine. Set aside.
Combine the vodka, yuzu, and simple syrup in a bowl or pourable container, such as a measuring cup. Whisk the liquids together to combine.
Divide the vodka mixture into 6 shooter glasses. There will be 2 ounces of liquid in each glass.
Place shucked oysters on the glass, then spoon 2 teaspoons of wasabi mignonette onto the half shell.