Whisk together oyster sauce, sesame oil, sherry, soy sauce, sugar, and cornstarch in a bowl until sugar is dissolved. Place steak in a shallow baking dish or bowl and pour oyster sauce mixture over it, coating well with your hands. Let sit for at least 30 minutes, covered in the refrigerator.
While the beef marinates, cook instant ramen according to directions on packet, without adding the spice packet. Drain, rinse, and set aside in a warm place while you continue cooking.
Heat olive oil in a large skillet over medium-high heat. Cook minced garlic for 30 seconds to a minute until soft and fragrant.
Add broccoli and cook for five to seven minutes or until bright green and tender. Place cooked broccoli in a bowl, cover, and set aside.
Add beef to the same skillet with the oyster sauce mixture. Cook for about five minutes until sauce thickens and creates a glaze and meat is fully cooked. Add broccoli to the beef and stir until coated and heated through. Continue cooking for three more minutes.
Divide the cooked ramen between four plates, and place beef and broccoli mixture over the noodles.