In a small bowl, whisk together the egg(s) and water until frothy.
Season generously with salt and pepper and set aside.
Heat the sun-dried tomato oil in a small nonstick skillet over medium heat.
Add the chopped shallot and sun-dried tomato, sautéing for 2-3 minutes until the shallot softens and becomes fragrant.
Add the arugula to the skillet and cook, stirring occasionally, for another 2-3 minutes until the leaves are just wilted.
Pour the egg mixture into the skillet, gently stirring to distribute the fillings evenly.
Reduce the heat to medium-low and let it cook for about 2 minutes, or until the edges begin to set.
Dollop the ricotta cheese over one half of the omelet.
Continue to cook for 1-2 more minutes, until the eggs are set but still tender. Gently fold the other half over the ricotta to create a half-moon shape. Slide onto a plate and serve immediately.
Don't have arugula? Fresh spinach or finely chopped kale are excellent substitutes. Wilt them in the pan just as you would the arugula.