In a small bowl, combine the scallions, cilantro, lime juice, olive oil, jalapeños and their brine, soy sauce, and mix well. Add salt if needed and set aside.
Sprinkle the fish with salt and pepper. Heat oil in a large skillet over medium-high heat until hot but not smoking. Add the fish, in batches to avoid crowding, and sear for about 3 minutes, until thoroughly browned on the bottom, so they release easily from the pan. Turn and sear for about 3 minutes on the second side. The fish is ready when the thickest part is cooked through and it flakes easily with a fork.