FOR THE POACHED EGGS
1 tablespoon white vinegar
4 large eggs
FOR THE SALAD
3 tablespoons extra-virgin olive oil
4 fingerling potatoes (about 12 ounces), blanched and sliced crosswise 1/2 inch thick
5 ounces baby spinach
2 links cooked (not dried) chorizo, sliced crosswise 1/2 inch thick
FOR THE DRESSING
2 tablespoons minced shallot
1 tablespoon sherry vinegar
Coarse salt and freshly ground pepper
Poach the eggs: Add vinegar to a large saucepan of simmering water. Crack eggs into water, 1 at a time. Poach eggs until whites are set but yolks are still runny, about 2 minutes. Transfer to a paper-towel-lined plate using a slotted spoon.
Make the salad: Heat 2 tablespoons oil in a high-sided skillet over medium heat. Cook potatoes until golden, about 6 minutes per side. Transfer to a large bowl using a slotted spoon, and add spinach. Add remaining tablespoon oil to skillet. Cook chorizo until golden brown, about 3 minutes per side. Add to bowl using slotted spoon.
Make the dressing: Remove skillet from heat. Add shallot, and let cook for 30 seconds. Swirl in vinegar.
Pour dressing over salad, season with salt and pepper, and toss to coat. Divide salad among 4 plates. Top each with an egg.