1. Prepare grill.
2. Snap off tough ends of asparagus or trim with a knife, and peel the bottom half of the stalk, if necessary.
3. Place asparagus on a baking sheet, toss with olive oil, and season with 1/4 teaspoon salt and 1/4 teaspoon pepper. Grill asparagus, perpendicular to the grates, for 3–5 minutes on each side or until just crisp-tender.
4. Grill the bread about 1 minute per side or until slightly charred. Cut each slice into 1-inch cubes.
5. Whisk vinegar, garlic, remaining 1/4 teaspoon salt and 1/4 teaspoon pepper, and extra-virgin olive oil in a large bowl until combined. Add asparagus, grilled bread, tomatoes, and remaining ingredients; mix. Season with more salt and pepper, if desired. Let sit at room temperature for at least 30 minutes.