Preheat your oven to 425°F and line a large sheet pan with parchment paper.
Halve the baby gold potatoes and place them on the sheet pan, tossing with half of the olive oil, half of the sea salt, and half of the black pepper.
Roast the potatoes for 15 minutes until they begin to soften.
While the potatoes roast, finely mince the garlic cloves and chop the fresh rosemary and thyme.
Pat the sirloin steak dry with a paper towel and rub it with the remaining olive oil, minced garlic, rosemary, thyme, and the rest of the salt and pepper.
Remove the pan from the oven, move the potatoes to one side, and place the steak and trimmed green beans on the other side.
Return the pan to the oven and roast for 10 to 12 minutes, or until the steak reaches an internal temperature of 135°F for medium-rare and the potatoes are fork-tender.
Remove from the oven and let the steak rest on a cutting board for 5 minutes before slicing against the grain to serve.