Using the grinder attachment on a mixer or in a food processor grind onion and potato together. Add shrimp and pulse all together.
In a bowl, combine the shrimp mixture with the chopped parsley, green onion and green pepper. Stir in the egg and flour to make a batter. Fold in shrimp to the mixture and season with salt and pepper.
Melt the shortening in a large skillet over medium-high heat. When the shortening is hot, drop the batter by tablespoonfuls into the pan. Saute 2 to 3 minutes per side, until browned and crisp. Drain on paper towels. Serve immediately.