In a shallow bowl, combine jalapeño slices with 1/4 cup each of the lime juice and olive oil. Rub chicken with salt and pepper; add to marinade. Marinate in the refrigerator for at least 30 minutes.

In a medium bowl, combine orange, grapefruit, scallions, tomatoes, remaining tablespoon each lime juice and olive oil, zests, salt and pepper, diced jalapeño, cilantro and tomatillos. Set aside.

Remove chicken from marinade. Cook on a hot grill for about 5 minutes on each side, or until cooked through. Remove from the grill, and let stand for 5 minutes.

Divide greens among four plates. Slice chicken, and arrange it on top of greens. Spoon salsa over each salad, and serve immediately.