Melt the butter in a large saucepan. Stir in the rice to coat with the butter. Add four cups boiling water and the salt. When the water comes back to a boil, stir it once, reduce the heat to low and cover tightly. Cook for 20 minutes.
Fluff with a fork and then add the oil, vinegar and salt and pepper to taste. Allow to cool.
Chop the red and green pepper into 1/8-inch dice. Peel and seed the cucumber, and cut it into a fine dice. Slice the scallions into very thin rounds. Chop the hard boiled eggs coarsely. Toss the chopped vegetables and chopped eggs with the rice and the chopped parsley and garnish with the grape tomatoes.