For the filling:
½ small shallot, finely chopped
6 ounces fresh blue crab meat, picked over
⅓ cup mascarpone
1 tablespoon finely chopped fresh chives
For the batter:
4 cups Cilantro and Roasted Onion Olive Oil, for frying
1 cup flour
⅓ cup cornstarch
1 tablespoon baking powder
½ teaspoon kosher salt, plus extra for finishing
1 cup amber lager
Make the filling: Combine first four ingredients in a medium bowl and season with salt. Gently fold to combine, and set aside.
Make the batter: In a large saucepan fitted with a deep-fry thermometer, pour Cilantro and Roasted Onion Olive Oil to a depth of 6 inches. Heat over medium-high heat until thermometer registers 375 degrees. While oil is heating, whisk together flour, cornstarch, baking powder, and salt in a large bowl. Gradually whisk in beer until just blended.
Working in batches of about four beignets at a time, and returning oil to 375 degrees between batches, measure 1 heaping tablespoon crab mixture, roll into a ball, and drop into batter. Using a fork, toss to coat and lift from batter, letting excess drip back into bowl. Carefully lower beignet into oil. Fry, turning occasionally, until crisp and deep golden brown, about 4 minutes. Transfer to a paper towel-lined plate and season with salt.