Wash the bell pepper and zucchini. Cut the bell pepper into wide strips and remove the seed membranes. Cut the zucchini into slices approximately one centimeter thick and finely chop the fresh rosemary. Combine the vegetables in a bowl with half of the olive oil, the rosemary, and a pinch of sea salt and black pepper. Pat the round steak completely dry with paper towels and season both sides with sea salt and freshly ground black pepper.
Heat a grill pan over medium-high heat and let it get very hot. Place the bell pepper and zucchini pieces in the pan and grill them for five to seven minutes per side. Remove the vegetables from the pan once they are tender and have clear grill marks, and set them aside.
Heat the remaining olive oil in a skillet over high heat. Place the steak in the pan once the oil begins to shimmer. Fry the meat for two to four minutes per side, depending on the desired degree of doneness.
Remove the steak from the pan and place it on a cutting board. Loosely cover the meat with a piece of aluminum foil. Let the steak rest for five minutes so the meat juices can redistribute properly.
Slice the steak with a sharp knife against the grain. Distribute the grilled bell pepper and zucchini over the plates and place the sliced round steak right next to them.