It usually takes 3 to 6 days for a person to get symptoms of hand-foot-and-mouth disease after being exposed to the virus. This is called the incubation period.
Preheat oven to 400 degrees F. Cut off the brown ends of the Brussels sprouts and pull off any yellow outer leaves. Mix them in a bowl with the olive oil, salt and pepper. Pour them on a sheet pan and roast for 35 to 40 minutes, until crisp on the outside and tender on the inside. Shake the pan from time to time to brown the sprouts evenly. Sprinkle with more kosher salt (I like these salty like French fries), and serve immediately.
Heat olive oil in a cast-iron skillet over medium heat until the oil shimmers, and cook garlic, stirring often, until golden brown and fragrant, about 3 minutes. Stir in onion and cook until soft, stirring often, about 5 minutes. Add Brussels sprouts to the skillet and cook without stirring until the undersides of the sprouts turn golden brown, 5 to 7 minutes. Stir to turn sprouts over, and cook other sides until golden brown, another 5 to 7 minutes. Season with salt, black pepper, and garlic powder.