Gently chop boiled eggs to small cubes and add them to a mixing bowl.
Add mayonnaise, red chilli flakes, dried herbs, parsley, black pepper, mustard, garlic and onion.
Mix well and taste it. If needed then add salt and vinegar or lemon juice
Optionally butter the bread slices and toast them on a griddle or in a toaster.
You can also toast them in a preheated oven at 350 F or 180 C for 3 to 4minutes. Adjust the grill time as desired. Over toasting will make it hard.
Cool them slightly, then spread the prepared egg salad on a bread slice.
Cover with another slice. Cut the sandwich with a serrated knife.
Serve egg mayo sandwich within 2 hours of preparing or chill in refrigerator.