4 skinless, boneless chicken breast halves (about 6 ounces each)
Salt and freshly ground pepper
1/4 cup all-purpose flour
3 tablespoons extra-virgin olive oil
Three 5-ounce bags baby spinach
1 leek, halved lengthwise and thinly sliced crosswise
2 garlic cloves, thinly sliced
2 tablespoons minced parsley
1 tablespoon minced tarragon
2 tablespoons fresh lemon juice
2 tablespoons dried currants
Lightly pound the chicken breasts 1/2 inch thick. Season with salt and pepper and dust with the flour. Heat 2 tablespoons of the olive oil in a very large skillet until shimmering. Add the chicken and sauté over moderately high heat until cooked through, 8 minutes. Transfer to a platter, cover and keep warm.
Wipe out the skillet. Add the spinach in batches and cook over moderately high heat, tossing, until wilted; transfer to a colander. Press to remove the liquid.
Wipe out the skillet; add the remaining 1 tablespoon of olive oil. Add the leek and garlic and cook over moderately high heat until softened, 2 minutes. Add the spinach, parsley and tarragon and toss. Add the lemon juice and currants; season with salt and pepper. Spread the spinach on plates, arrange the chicken on top and serve.