Heat oil in large non stick skillet over medium heat. Add onion; cook, stirring about 3 minutes. Add potatoes; cook until tender and golden, about 8 minutes. Season with salt. Which eggs in large bowl. Stir in onion/potato mixture, sweet pepper and parsley, if using. Pour egg mixture into skillet over medium heat; cook 1 minute. Reduce heat to low; cook until eggs are set in centre and lightly browned on bottom. Slide omelette onto large flat plate. Place another plate on top; flip to invert. Slide back into skillet; cook 2 to 3 minutes longer.
Oven Method: Pour potato/egg mixture into a 9 inch (23 cm) pie plate brushed well with olive oil. Bake in 325 F (160° C) oven for 35 minutes or until set in centre.