Pat the steak cubes dry with paper towels. Season with 1/2 teaspoon kosher salt, 1/4 teaspoon black pepper, and smoked paprika. Set aside.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat until shimmering.
Add the steak bites in a single layer, cooking in batches if necessary to avoid overcrowding. Sear for 2-3 minutes without moving, then flip and cook for another 2-3 minutes until browned and cooked to desired doneness. Remove steak bites from skillet and set aside on a plate.
Reduce heat to medium and add 2 tablespoons of butter to the same skillet. Add minced garlic and cook for 30 seconds until fragrant.
Return the steak bites to the skillet, tossing to coat in the garlic butter. Cook for 1 minute, then remove from heat.
In a separate large skillet, melt remaining 2 tablespoons butter over medium heat.
Add sliced zucchini, season with remaining 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. Sauté for 5-7 minutes, stirring occasionally, until zucchini is tender and slightly golden.
Transfer zucchini to serving plates. Spoon garlic butter steak bites over or alongside the zucchini.
Garnish with chopped fresh parsley and serve immediately.