Heat a large sauté pan over medium heat and add in the oil. When the oil is hot, add in the onions and cook for 2-3 minutes or until they start to soften. Add in the garlic and cook for another minute. Raise the heat to medium-high and add in the snap peas. Cook, stirring frequently, for one minute, then stir in the marinade. Set heat to medium-low and let the mixture simmer for about a minute before removing from the heat.
While the snap peas cook, heat a medium sauté pan over medium-high heat. Dry off the scallops on paper towels, then place them on a plate and dip both sides of each scallop into the spice rub. When the pan is hot, add the oil to the pan and give it a few seconds to heat up. When the oil is hot and shimmering, place the scallops in the pan on one of the spice-rubbed sides. Let the scallops sit without disturbing them for a minute and a half. If the pan starts to smoke a lot, reduce the heat slightly. Cook the opposite sides of the scallops for a minute and a half before removing them to serving plates.
Divide snap peas and scallops between plates and serve warm alongside a salad or another side dish.