⅛ tsp. crushed red chile flakes 2 cloves garlic 1 oil-packed anchovy filet (see note) Kosher salt, to taste Rind of ½ preserved lemon, roughly chopped ¼ cup loosely packed fresh oregano leaves 1½ tbsp. red wine vinegar 6 tbsp. extra-virgin olive oil Freshly ground black pepper, to taste 1 lb. large spinach leaves
1. Place the chile flakes, garlic, anchovy, and a pinch of salt in a mortar and smash with the pestle until ingredients are finely ground. Add the lemon and oregano and continue smashing until the oregano has broken down into tiny pieces. (Alternatively, put the garlic, anchovy, salt, lemon, and oregano on a cutting board, finely chop with a large knife, and transfer to a bowl; stir in chile flakes.) Add vinegar, whisk in olive oil, and season with salt and pepper. Cover with plastic wrap and let vinaigrette sit for at least 30 minutes.
2. To serve, put spinach into a large serving bowl. Drizzle vinaigrette over spinach, season with salt and pepper, and toss vigorously with your hands until the spinach is thoroughly coated with the vinaigrette.
Note: To make this recipe vegetarian or vegan: Omit the anchovy and replace with ½ ounce black olive tapenade.