Trim the fat from the sirloin steak. Cut the steak into strips against the grain. Salt and pepper generously and let the meat "rest" at room temperature for 20 minutes (this will avoid it getting hard when it hits the pan).
Chop the onions finely in half-moon slices. Heat 1 tbsp of coconut (olive) oil in a wok or large frying pan on high heat and saute the onions, stirring them around occasionally for 3-4 minutes. When they are translucent and barely tender, add 1 tsp of curry powder and stir to coat all the onions. Continue to cook until they start to become crispy and the bottom of the pan begins to brown. Add the water and scrape the bottom of the pan with a wooden spoon. Let the onions simmer on high heat for a few more minutes until they are tender, then remove from the pan and transfer to a bowl.
In the same pan, heat the remaining coconut (olive) oil on high heat. Once it is hot and starts to smoke, add the steak strips and let them brown on one side for a minute, then stir around and cook for another minute. Add the remaining curry powder, the garlic and ginger and cook for 3 more minutes (for well-done meat). Add the onions, parsley and chopped scallions to the pan, stir around to combine the ingredients and serve topped with sesame seeds.