How to Make It
Light a grill or heat a grill pan. Brush the lemon slices with olive oil and grill over moderate heat, turning occasionally, until lightly charred and the rind is tender, about 8 minutes. Transfer to a work surface and let cool, then finely chop.
In a small bowl, whisk the chopped lemon with the celery, shallot, parsley, 1/4 cup of olive oil and 1/2 teaspoon each of the rosemary, thyme and oregano. Season with salt and pepper.
Brush the swordfish with oil and season with salt, pepper and the remaining 1 1/2 teaspoons each of the dried herbs. Grill the fish over moderately high heat, turning once, until lightly charred and just cooked through, 8 minutes. Transfer to plates and serve with the salsa.