Grilled Burgers with Meyer Lemon Butter

Preparation Mix butter, all herbs, lemon peel, and lemon juice in small bowl. Season with salt and pepper. Measure 1/3 cup herb butter; transfer to sheet of plastic wrap (reserve remaining butter in bowl for spreading on buns). Using plastic wrap as aid, form butter into 3-inch-long log; wrap plastic around to seal. Freeze until firm, about 30 minutes. Cut crosswise into 4 rounds. Flatten rounds into 2-inch-diameter disks. Divide meat into 4 equal pieces. Using damp hands, form each piece into ball. Using thumb, make deep wide indentation in center of each ball. Press 1 lemon-butter round flatly into indentation, then press meat securely over butter to enclose. Flatten each burger into 31/2-inch-diameter patty, leaving butter rounds horizontally in center of each burger. DO AHEAD: Herb butter and burgers can be made 6 hours ahead. Place burgers on baking sheet, cover with plastic wrap, and chill. Cover and chill herb butter in bowl; bring to room temperature before continuing. Brush barbecue rack with oil. Prepare barbecue (high heat). Sprinkle both sides of burgers with salt and pepper. Spread remaining butter over cut sides of buns. Grill burgers until cooked through, 4 to 6 minutes per side. Grill buns until slightly charred, about 1 minute per side. Place burgers on bun bottoms. Top with tomato slices and arugula leaves. Cover with bun tops and serve.

Preparation Mix butter, all herbs, lemon peel, and lemon juice in small bowl. Season with salt and pepper. Measure 1/3 cup herb butter; transfer to sheet of plastic wrap (reserve remaining butter in bowl for spreading on buns). Using plastic wrap as aid, form butter into 3-inch-long log; wrap plastic around to seal. Freeze until firm, about 30 minutes. Cut crosswise into 4 rounds. Flatten rounds into 2-inch-diameter disks. Divide meat into 4 equal pieces. Using damp hands, form each piece into ball. Using thumb, make deep wide indentation in center of each ball. Press 1 lemon-butter round flatly into indentation, then press meat securely over butter to enclose. Flatten each burger into 31/2-inch-diameter patty, leaving butter rounds horizontally in center of each burger. DO AHEAD: Herb butter and burgers can be made 6 hours ahead. Place burgers on baking sheet, cover with plastic wrap, and chill. Cover and chill herb butter in bowl; bring to room temperature before continuing. Brush barbecue rack with oil. Prepare barbecue (high heat). Sprinkle both sides of burgers with salt and pepper. Spread remaining butter over cut sides of buns. Grill burgers until cooked through, 4 to 6 minutes per side. Grill buns until slightly charred, about 1 minute per side. Place burgers on bun bottoms. Top with tomato slices and arugula leaves. Cover with bun tops and serve.