Pat the steak dry with paper towels. Slice the steak against the grain into thin strips, about 1/4-inch thick. In a medium bowl, toss the steak strips with 1 tbsp olive oil, garlic powder, onion powder, 1/2 tsp salt, and black pepper. Let marinate at room temperature for at least 15 minutes, or up to 30 minutes for more flavor.

Preheat your air fryer to 375°F (190°C). If using an oven, preheat to 400°F (200°C).

Brush both sides of the baguette slices with 2 tbsp olive oil and sprinkle lightly with 1/4 tsp garlic powder and a pinch of salt. Arrange in a single layer in the air fryer basket (working in batches if necessary) or on a baking sheet.

Air fry for 5-7 minutes, flipping halfway, until golden brown and crisp. For the oven, bake for 7-10 minutes, flipping halfway. Set aside.

While the crostini are toasting, pour the balsamic vinegar into a small saucepan. Bring to a simmer over medium heat. Reduce heat to low and continue to simmer, stirring occasionally, for 5-7 minutes, or until the vinegar has thickened to a syrupy consistency and coats the back of a spoon. Be careful not to over-reduce; it will thicken further as it cools. Remove from heat and set aside.

Heat a cast iron skillet over medium-high heat until very hot. Add the marinated steak strips in a single layer (cook in batches if needed to avoid overcrowding). Sear for 1-2 minutes per side for medium-rare, or longer for desired doneness. Remove steak from skillet and let rest on a cutting board for 2-3 minutes before slicing into bite-sized pieces if they are too large.

To assemble, place a few pieces of seared steak onto each toasted crostini. Top with a piece of torn burrata cheese. Drizzle generously with the balsamic glaze.

Garnish with fresh chopped chives and optional parsley. Serve immediately.