Soak wooden skewers in water for at least 30 minutes.
In a large bowl, mix olive oil, balsamic vinegar, honey dijon mustard, garlic powder, kosher salt, and black pepper. Add steak cubes and toss. Cover and refrigerate for 1 hour.
Remove steak from fridge and let come to room temperature for 30 minutes.
Thread one grape tomato, three steak cubes, another tomato, three more steak cubes, and finish with a tomato on each skewer.
In a small bowl, mix olive oil, basil, garlic, red pepper flakes, and flaky salt to make the herb oil. Set aside.
Preheat grill to high heat (about 450–500°F). Clean grates with a halved onion.
Grill skewers 5–6 minutes per side until steak is charred and cooked to desired doneness and tomatoes are blistered.
Remove from grill. Sprinkle with flaky salt and pepper, drizzle with balsamic glaze, then top with torn burrata, and spoon herb oil over the top.