Place eggs in a saucepan covered by an inch or two of cold water. Bring to a full boil, then cover and remove from heat. Let sit, off the heat, for 10 minutes, then transfer with a slotted spoon and into a bowl filled with ice water to stop the cooking process.Once cool, peel eggs, then coarsely chop and place in a bowl along with mayo, mustard, paprika, salt and pepper. Fold to combine.To assemble, arrange a single layer of beet on a piece of toasted bread. Top with half of egg mixture, and a handful of greens, followed by another piece of bread. Cut in half and serve immediately.