To make the vinaigrette, in a blender, combine the canola oil, olive oil, vinegar and mustard and blend until fully incorporated. Season with salt and pepper. Set the vinaigrette aside.

Fill a large saucepan with water and bring to a boil over high heat. Salt the water so it tastes like seawater. Fill a large bowl or casserole dish with equal amounts of cold water and ice to create an ice bath.

Add the brussels sprouts to the boiling water and cook until tender, 2 to 3 minutes; do not cook too long or they will lose their bright green color. Remove the brussels sprouts from the water and shock them in the ice bath to stop the cooking. Let the brussels sprouts stand in the ice bath until cool, then remove them and set aside.

In a large sauté pan over medium-high heat, add the bacon and cook until the fat renders and the bacon crisps, about 7 minutes. Add the onion to the pan and cook until softened, about 5 minutes. Add the butter and let it melt, then add the apples and thyme sprigs. Toss to coat and cook for 1 to 2 minutes. Add the blanched brussels sprouts and season with salt and pepper. Cook, stirring occasionally, until the sprouts are golden brown, 8 to 10 minutes. Remove the thyme sprigs and discard.

Drizzle half of the vinaigrette over the brussels sprouts and toss to coat. Transfer to a serving bowl and serve immediately. Pass the remaining vinaigrette alongside. Serves 4 to 6.