Two 3-inch wide long loaves French crusty bread (8 inches of bread per sandwich), split
For the pesto: In a food processor, combine the basil, peas, Parm, mint, tarragon, garlic and about 1/2 cup EVOO. Season with salt and pepper and process to almost smooth. Transfer to a small container until ready to use. Or refrigerate and bring to room temperature when ready to serve.
For the beef: Bring the roast to room temperature. Sprinkle the meat with the salt, pepper and rosemary.
Preheat the oven to 475 degrees F.
Heat 2 tablespoons EVOO in a Dutch oven or large cast-iron skillet over medium-high heat. Brown the meat evenly, 5 minutes. Then transfer to the oven and roast 30 minutes, or until the internal temperature registers 120 degrees F on a meat thermometer.
Transfer the roast to a cutting board and cover with foil, 30 minutes. Wrap and store if not serving right away.
To serve, very thinly slice the meat. Heat the stock to warm but not boiling. Quickly dip the meat in the stock and place on the French bread. Top with the green pea pesto and set the bun top in place.