How to Make It
In a food processor, blend the butter with the coarsely chopped basil, 2 tablespoons of the capers, the lemon zest and the garlic until almost smooth. Season with salt and pepper and transfer to a small bowl.
In a bowl, toss the tomatoes with the onion, olive oil, vinegar, orange zest and saffron. Season with salt and pepper.
Heat the canola oil in a large heavy skillet until almost smoking. Season the steaks, add them to the skillet and cook over high heat until well browned on all sides, about 10 minutes. Transfer to a platter and pour off the fat from the skillet. Return the meat to the skillet and add the basil butter. Lower the heat to moderately high and cook, basting the meat continuously with the butter sauce, 6 to 8 minutes for medium rare. Remove the pan from the heat, return the steaks to the platter and cover loosely with foil. Add the remaining 1 1/2 tablespoons of capers and the shredded basil to the skillet.
Arrange the grilled asparagus on 4 large plates and spoon the tomato vinaigrette alongside. Set the sautèed steaks on the vinaigrette and spoon the caper butter sauce on top. Garnish with the basil sprigs and serve at once.