In a small bowl stir together the tomato, the onion, the jalapeño, the coriander, the lime juice, and salt and pepper to taste until the salsa is combined well. In a bowl whisk together the eggs, the water, and salt and pepper to taste.
In a 8-inch skillet, preferably non-stick, heat 1/2 tablespoon of the butter over moderately high heat until the foam subsides, pour in half the egg mixture evenly over the bottom, and cook it for 1 minute, or until it is almost set. Sprinkle half the omelet with half the bacon, half the avocado, peeled and cut into 1/2-inch pieces, and half the Monterey Jack and cook the omelet for 1 minute, or until it is set. Fold the omelet over the filing, transfer it to a plate, and keep it warm. Make another omelet in the same manner with the remaining butter, egg mixture, bacon, avocado, and Monterey Jack and serve the omelets with the salsa.