In a medium frying pan, heat ¼ cup olive oil over medium heat. After about a minute, test oil by flicking a drop of water in it. If it sizzles, add sliced leek greens and distribute in an even layer across pan. Let leeks fry until they begin to turn golden (1-3 minutes depending on oil temperature), then remove from heat and use a silicone spatula or wooden spoon to remove leeks; set aside in a bowl to cool.

Pour oil into a bigger bowl or small glass jar in which you can mix the salad dressing. Add vinegar and sea salt and whisk vigorously. Taste, and add more salt, if desired.

In same pan, evenly distribute strips of halloumi. Return to medium heat and grill until they begin to sizzle and bubble. About 30 seconds longer, and they’ll start to brown. You can flip if you want to brown both sides, or leave one side smooth and creamy, and the other crisp. Remove when they’ve reached desired level of crispness, about a minute longer. Remove from heat and transfer crispy cheese to a small bowl or plate.

Assemble salad by layering torn lettuce leaves, sliced fennel, apple, and persimmon, and topping with crispy halloumi. Drizzle with vinaigrette, and enjoy.