For the steak: Place the steak, olive oil, cumin, garlic powder, onion powder, salt, black pepper, cayenne, garlic and onions in a resealable plastic bag. Shuffle in the bag for 20 seconds to cover the steak completely in the rub marinade. Let sit for at least 30 minutes if time allows.
For the onion rings: Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper.
Separate the onion rings and place in another resealable plastic bag.
In one bowl, whisk the half-and-half and eggs together. Add the breadcrumbs to a second bowl and in a third bowl whisk the flour with the salt, black pepper, garlic powder, onion powder and cayenne.
Add the flour mixture to the bag with the onions and toss well. Then dip the onions into the eggs and then dredge in the panko, pressing to coat.
Spread the onion rings on the prepared baking sheet in an even layer. Coat with vegetable oil spray and bake in the oven until crispy, 20 to 25 minutes.
Meanwhile, remove the steak from the bag. Lightly oil a grill pan and heat over medium-high heat. Cook the steak until desired doneness, 3 to 4 minutes on each side. Let rest for 5 minutes.
Remove the onion rings from the oven. Slice the steak into strips and place in the center of a plate. Top with a stack of onion rings.