Grilled Steak with Sauce Vierge

Name: Grilled Steak with Sauce Vierge
Ingredients: 1⁄4 cup roughly chopped flat-leaf parsley; 1 tbsp. capers; 12 large green olives, such as cerignola, pitted and roughly chopped; 6 oil-packed anchovy filets, drained and finely chopped; 4 cornichons, roughly chopped; 1 shallot, roughly chopped; 1 clove garlic, finely chopped; 1 jalapeño, stemmed and finely chopped; 1⁄2 cup extra-virgin olive oil; 1 tbsp. dijon mustard; Kosher salt and freshly ground black pepper, to taste; 4 (½”-thick) top sirloin steaks (about 2 lbs.)