Cut the flour tortillas into 30 rounds with a 3.5 to 4-inch circle cutter. Uniform rounds fold neatly and make evenly sized dessert tacos.

Pour 1 inch of oil into a deep pan and heat it over medium heat, then lower in a tortilla round with tongs. Gentle bubbles should gather around the edges within about 10 seconds.

Turn the round, then use the tongs to fold it in half and hold the shape briefly as it fries. Keep turning as needed until both sides are golden brown and the shell feels firm.

Transfer the hot shell straight into the light brown sugar and coat it all over, then rest it over an upside-down muffin tin. The sugar adheres best while the shell is hot, and the tin helps preserve the taco shape as it cools.

Repeat with the remaining tortilla rounds. Arrange finished shells with space between them so their crisp surfaces stay dry.

Combine the blueberries, granulated sugar, 5 Tablespoon water, lemon juice, and lemon zest in a medium pan over medium heat and cook for 10 minutes. The berries should soften and release a vivid purple juice as the mixture gently bubbles.

Stir the remaining 2 Tablespoon water with the cornstarch in a small dish, then mix the slurry into the simmering berries. Cook for 20 to 30 seconds, until the sauce looks glossy and coats the back of a spoon.

Remove the pan from the heat and let the blueberry sauce cool completely. The sauce should be at room temperature and thick enough to mound softly on a spoon before assembly.

Whip the heavy whipping cream until stiff peaks form, then set it aside. The peak should stand upright on the whisk rather than drooping over.

Beat the softened cream cheese, powdered sugar, and lemon juice at medium speed until smooth. Stop once the mixture is creamy and free of visible cream cheese bits.

Fold the whipped cream into the cream cheese mixture with a light hand. The finished filling should look fluffy while holding its shape.

Spoon the filling into a piping bag and trim the tip, then pipe it into the cooled taco shells and add blueberry sauce on top. Fill just before serving so the shell stays crisp against the cool cream.