For frying: Heat the oil in a large Dutch oven to 350 degrees F.

For the filling: Melt the butter in a small skillet over medium heat. Add the shallots, garlic and a large pinch of salt and sweat, stirring occasionally, until softened but not brown, 2 to 3 minutes. Season with salt and pepper and set aside to cool.

Mix together the ricotta, mascarpone, chives, tarragon and lemon zest in a large bowl. Stir in the garlic-shallot mixture and season with salt and pepper. Fold in the crabmeat. Chill in the fridge at least 15 minutes or up to 1 day before stuffing.

Shape 15 heaping tablespoons of the filling into ovals the size of the squash blossoms. Carefully open each blossom and gently nestle the pre-shaped filling inside, pressing the petals around the filling to seal. Keep refrigerated while you make the batter, or up to 1 day in advance.

Meanwhile, make the batter: Whisk together the all-purpose flour, rice flour, cornstarch, baking powder and salt in a large bowl. Gradually whisk in the soda water until it coats your fingers.

Dip each blossom in the batter and allow excess to drain off slightly. Working in 2 batches, carefully place the blossoms in the Dutch oven and cook until golden brown, 1 to 2 minutes per side. Use a slotted spoon to remove the blossoms to a paper towel-lined plate, sprinkle with salt immediately and repeat with the remaining blossoms.