Preheat a medium to large pot (with tight-fitting lid) with cooking oil. When hot enough, add in the onion and cook until it's soft, about 3-4 minutes (take care not to burn the onion). Add in the rice and stir again to mix. Add in 2 cups of water/broth and bring to a boil. Then cover with a lid and lower the heat to medium and let it cook for the next 15 minutes undisturbed. The liquid will be absorbed by the rice at the end of cooking time. Let it sit for 10 minutes before opening the lid
Uncover the lid and fluff the rice with a fork. Then squeeze in juice of 1 lime, lime zest, cilantro, leaves, and salt and pepper (you may not need to salt it if you are serving with with savory dishes). Stir to mix everything. Ready to be served