Combine egg yolk, mustard and pinch of salt in a medium bowl. Anchor bowl by setting it inside a towel lined saucepan, which will afford you 2 free hands... 1 for pouring and 1 for whisking. Whisk until very smooth.
Combine olive and vegetable oils in a measuring cup and pour into yolk mixture, drop by drop at first, then in a slow steady stream as mixture stiffens, until all the oil has been added. Whisk in the vinegar and hot spice blend; season with salt and pepper. Thin mayo with water if needed, adding a teaspoonful at a time until just loose enough to fall off a spoon.
For Egg Salad and Assembly
To boil the eggs, put them in a pot of cold water to cover. Bring to a boil. Turn off heat and cover. Let sit on stove covered for 17 minutes. Immediately transfer eggs with a slotted spoon to a bowl of ice water and stir until cool enough to handle, about 1 minute. Drain, pat dry and peel eggs. Chop eggs into large pieces and add just enough mayonnaise to lightly coat. Taste for seasoning. Spoon over bread.
Toss scallions, basil, dill, chives and lemon zest in a small bowl. Add lemon balsamic, drizzle with oil and season with salt. Toss to coat. Pile herbs on top of egg. Drizzle with White Truffle Oil. Eat and enjoy.