Whisk eggs with water; season with pepper. Spray an 8 inch ( 20 cm) non stick skillet with cooking spray. Heat over medium high heat. Pour in egg mixture. As mixture sets at edges, with spatula, gently push cooked portion toward centre. Tilt and rotate the pan to allow uncooked egg to flow underneath. Cook until surface is set. Set aside to cool.
Spread mayonnaise on bottom half of bread. Spread the other half with sun-dried tomato pesto. Arrange roasted red pepper and then the omelette on bottom piece. Cover with feta cheese and then with basil. Top with remaining slice of focaccia.