Put greens in a large salad bowl. Put olive oil in a skillet over medium heat. When hot, add the bacon and cook slowly until crisp all over, about 10 minutes. Add vinegar and mustard to the skillet and bring just to a boil, stirring, then turn off heat.

Meanwhile, bring a couple inches of salted water to a boil in a small pan, then lower heat to barely bubbling. One at a time, break eggs into a shallow bowl and slip them into the bubbling water. Poach the eggs for 2 minutes, until the white is set but the yolk is still runny. Remove each egg with a slotted spoon, and place onto the greens.

Pour the bacon dressing over the greens (they’ll wilt a bit). Toss the salad, breaking the yolks of the poached eggs and distributing them evenly over the spinach. Season with salt and pepper to taste. Serve immediately, with croutons or toast if you like.

This hearty salad is quick and easy to make, yet fit for a king with the combination of meaty-leaved spinach, crisp bacon, barely cooked eggs, and warm, sharp Dijon vinaigrette.