Start by parboiling the sweet potato. Just 5 to 8 minutes in boiling water gets it fork-tender without making it mushy. Let it cool, then slice it into ¼-inch rounds.
Preheat your grill to medium-high. While it heats up, brush all your veggies – sweet potato, zucchini, and yellow squash – with olive oil and season both sides generously with za’atar.
Grill the sweet potatoes first – they’ll need 3 to 5 minutes per side. Flip when char marks appear, and they feel tender. Transfer to a serving plate once cooked.
To finish, drizzle everything with pesto and sprinkle feta over the top. Garnish with a little extra sea salt, black pepper, and a bright splash of lemon juice.