In a small bowl or measuring pitcher, whisk together the olive oil, balsamic vinegar, Dijon mustard, and honey until well combined. Add the dried thyme, garlic powder, smoked paprika, salt, and black pepper, whisking until smooth and emulsified. This balanced marinade will coat the vegetables evenly and infuse them with savory, tangy flavors as they sit.

While the marinade rests, prepare all vegetables for grilling. Halve the carrots lengthwise, trim the woody ends from asparagus, slice zucchini into long planks (about 1/4-inch thick), cut yellow squash into 1/2-inch rounds, and slice the red bell pepper into wide strips. Having all vegetables cut and ready will speed up the marinating and grilling process. I find that cutting vegetables into similar thicknesses helps them cook more evenly on the grill.

Transfer all prepared vegetables to a large baking tray or shallow dish. Pour the marinade from Step 1 over the vegetables, gently tossing to coat everything evenly. Let the vegetables sit for 30 minutes at room temperature, stirring occasionally to redistribute the marinade. This resting time allows the flavors to penetrate the vegetables and helps keep them tender during grilling.

Preheat your grill to medium heat (around 350-400°F). Once hot, begin with the carrots as they require the longest cooking time—grill them for 3-4 minutes on the first side until lightly charred, then flip and cook another 2-3 minutes. Add the remaining vegetables (asparagus, zucchini, squash, and bell pepper) to the grill and cook for 8-10 minutes total, flipping once halfway through, until they develop light char marks and are tender-crisp. I like to reserve a bit of extra marinade to brush on the vegetables mid-way through grilling for extra flavor and moisture.

Transfer the grilled vegetables to a serving platter. Give everything a final squeeze of fresh lemon juice to brighten the flavors and add acidity that complements the sweet balsamic marinade. Serve immediately while the vegetables are still warm, or let cool to room temperature for a refreshing side dish.