Preheat your oven to 425°F and line a baking sheet with parchment paper.
Dice the russet potato into small, uniform half-inch cubes for maximum crispiness.
In a bowl, toss the potato cubes with 1 teaspoon of olive oil, smoked paprika, garlic powder, and half of the sea salt and black pepper.
Spread the potatoes in a single layer on the baking sheet and roast for 20-25 minutes, flipping halfway through, until golden brown.
While potatoes roast, season the sirloin steak with the remaining sea salt and black pepper.
Heat a cast-iron skillet over medium-high heat with the remaining 1 teaspoon of olive oil.
Sear the steak for 3-4 minutes per side for medium-rare, then remove from heat and let it rest for 5 minutes.
Finely dice the red bell pepper and slice the green onion.
Slice the rested steak against the grain into thin strips.
Plate the crispy potatoes and top them with the diced bell pepper, a dollop of Greek yogurt, and green onions. Serve the steak alongside.