In a small nonstick skillet or omelet pan, heat butter until sizzling over moderately low heat.
Meanwhile slit the pepper lengthwise and lay flat, remove seeds if less heat is desired; lay pepper on top of cheese slice; whisk water, eggs and dry seasonings together.
Add egg mixture to the sizzling butter and turn heat up to medium-high; stir the eggs with a fork for 15 seconds.
As the eggs begin to set, smooth them with the fork while shaking the pan over the heat; place the cheese slice and pepper across the omlette, perpendicular to the pan handle and off-center (closer to the handle).
Grab the pan handle from underneath, hold the serving plate next to the front of the pan (opposite the handle) and slide the first half of the omelet onto the plate, folding the second half over it by tilting the omelet pan up and over.