For the herby green sauce:
1/4 cup flat-leaf parsley leaves
1/4 cup mint leaves
2 Tbs. basil leaves
2 Tbs. capers
4 anchovy filets
1 garlic clove
2 Tbs. Dijon mustard
2 Tbs. red wine vinegar
Extra-virgin olive oil
Finely chop the herbs, garlic, capers, and anchovies and place the ingredients in a bowl. Stir in the mustard and vinegar. Add olive oil if the sauce is too thick to drizzle. Set aside.
For the steaks & onions:
2 (8- to 10-oz.) bison strip steaks
2 large green onions, sliced in half lengthways, with tops included
2 Tbs. canola oil (for steaks)
1 Tbs. extra-virgin olive oil (for onions)
Flaky sea salt
Sprinkle the steaks liberally with kosher salt. Heat the canola oil in a large cast-iron skillet over high heat until shimmering. Add the steaks, reduce the heat to medium-high, and sear them on one side until browned and caramelized, about four minutes. Check to be sure that the steaks are able to easily be turned over; sear a bit longer if not. Flip steaks; sear them on the other side for four minutes for rare and four minutes more for medium. Move the steaks to a cutting board, cover lightly with foil, and rest while cooking the onions. Keep the skillet on the stove.
Sprinkle the spring onions with salt and drizzle them with olive oil. Place them in the hot skillet cut side down and cook until tender when pierced with a knife, about seven minutes. Cut the steaks into 1/2-inch thick slices. Drizzle with the sauce, sprinkle with sea salt, and serve with the roasted onions.