Combine sour cream, horseradish, apple cider vinegar, mayonnaise, kosher salt, chives, Worcestershire sauce, and black pepper in a bowl to make the horseradish cream.

Preheat a grill or skillet over medium-high heat.

Brush sliced baguette with olive oil and grill until lightly toasted on both sides.

Rub halved garlic cloves on the toasted bread for flavor.

Season ribeye steak with kosher salt and cook to desired doneness, approximately 4-5 minutes per side for medium-rare.

Let steak rest for 5 minutes before slicing thinly against the grain.

Assemble crostini by placing slices of steak on toasted baguette, then top with horseradish cream and garnish with chives.