Use your fingers to carefully dig a hole on the side of the courgette flower, opening it enough to dig out with you pointer the pollen stem that is inside. Gently rinse the flowers under a sprinkle of cold water, paying attention not to damage the thin petals, then lay on a rag and pat dry.
Fill a piping bag with the ricotta cheese and pipe 2 to 3 tablespoons of the ricotta into each flower. Twist the petals to close tightly so the cheese doesn't escape during frying.
In a mixing bowl, whisk together the flour, parsley, a couple of generous pinches of salt and a few grinds of black pepper. Slowly start pouring the beer into the mix, using a whisk or a fork to make the batter; mix to eliminate any lumps.
Add the vegetable oil to the bottom of a heavy pan for deep frying until it comes up the sides 2 inches, making sure the oil is not more than halfway up the sides. Heat the vegetable oil until hot.
Dip the filled flowers through the batter then carefully add to the hot oil. Fry, flipping halfway through frying, until the blossoms are golden and crisp, 2 minutes.
Remove and place on a large dish lined with paper towels. Sprinkle with salt to taste while still hot.