Preheat your grill or a heavy cast-iron skillet over medium-high heat until it is very hot.
Pat the flank steak completely dry with paper towels to ensure a good sear, then season both sides evenly with sea salt, black pepper, and garlic powder.
Prepare the vegetables by slicing the zucchini into half-inch rounds, the bell pepper into wide strips, and the red onion into thick wedges.
In a large bowl, toss the sliced vegetables with the extra virgin olive oil and dried oregano until every piece is well-coated.
Place the steak on the grill and cook for approximately 4-5 minutes per side for medium-rare, or until it reaches your desired level of doneness.
Remove the steak from the heat and let it rest on a cutting board for at least 5-7 minutes to lock in the juices.
While the steak rests, place the vegetables on the grill or in the skillet, cooking for 6-8 minutes and turning occasionally until they are tender and show beautiful char marks.
Thinly slice the steak against the grain and serve it immediately alongside the vegetable medley with a fresh squeeze of lime juice over the top.