Heat a large skillet with olive oil. Add the asparagus spears, then cook, stirring occasionally, for 4-5 minutes (longer if the asparagus is thick, shorter if they are thin), until crisp-tender.
Add the grape tomato halves and cook for 2 minutes. Season with sea salt and freshly cracked pepper, to taste.
Place the asparagus and tomatoes on a serving plate, drizzle with good balsamic vinegar, and then top with feta cheese crumbles.