Preheat oven to 375 degrees.Separate the egg yolks from the whites and place each in a medium-sized mixing bowl .Beat the whites by hand with a whisk or with a hand mixer until firm and fluffy.Add the salt, honey, lemon juice, lemon zest and yogurt to the egg yolks and beat until smooth and fully incorporated.Gently whisk a third of the egg whites in to the egg yolk mixture then gently fold in the rest until incorporated being careful to not deflate the egg whites.Heat the butter or oil an 8 or 9- inch ovenproof skillet , over medium-low heat.Pour the mixture into the skillet (pan will be very full) and cook for 1-2 minutes, just until set on the bottom. Gently sprinkle the blueberries across the top and then transfer skillet to the pre-heated oven.Bake for about 15 minutes, until puffed and browned on top and set in the center.Remove skillet from oven and let cool slightly on a wire rack.Serve warm or at room temperature with a dollop of yogurt and extra fruit on the side.