Place a single layer of cauliflower in a food processor fitted with the steel blade.
Pulse until the cauliflower is a little larger than the size of rice, then transfer into a microwave-safe bowl.
Repeat with the remaining cauliflower.
Cover the bowl and microwave the cauliflower at 100% for 5 minutes.
Spread the cauliflower onto a clean dish towel and let it sit until it’s cool enough to handle, about 10 minutes.
Bring the edges of the towel together to form a pouch. While holding the cauliflower rice over a bowl, twist and squeeze to remove as much liquid from the cauliflower as possible.
Heat the oil over medium heat in a large skillet or wok. Once hot, add the onions and sauté, stirring constantly, until translucent and soft, about 5 minutes.
Add the garlic, ginger, and salt, then cook for an additional minute, stirring constantly.
Add the cauliflower and cook, stirring often, until heated through, about 5 minutes.