Make the glaze: microwave the frozen blueberries in a microwave-safe bowl until softened, 30 to 60 seconds. Smash with a muddler, then pass through a fine mesh strainer. Stir in lemon juice, water, and lemon zest. Slowly add powdered sugar and whisk until it forms a thick glaze.
Combine butter, water, milk, sugar, and a pinch of salt in a pot. Cook over medium heat until butter has melted and mixture is beginning to simmer.
Remove the pot from the heat and whisk in the flour until there are no clumps. Switch to a spatula and return pot to the stove. Cook over medium heat, stirring constantly, for 2 to 3 minutes. A film will form on the bottom of the pot.
Transfer batter to a stand mixer and mix on low speed with a paddle attachment to cool, about 3 minutes.
Add the eggs one at a time, mixing after each addition until fully incorporated.
Scoop finished choux pastry into a piping bag fitted with a large star tip. Pipe 3-inch crullers onto greased pieces of parchment paper.
Heat oil in a deep saucepan over medium heat until a thermometer reads 375 degrees F (190 degrees C). Lower 2 to 3 crullers at a time carefully into the hot oil Fry until deep golden brown and doubled in size, 3 to 4 minutes per side. Transfer to a paper towel-lined plate to drain and cool for 1 minute.
Dip crullers into the blueberry glaze and set on a wire rack to dry.
