Add the parsley, basil, cilantro, red onion, garlic, ⅓ cup olive oil, red wine vinegar, lemon juice, and a pinch each of salt and pepper to a food processor. Pulse until everything is combined but the sauce is still a little chunky, stopping to scrape down the sides of the bowl as needed. For a thinner sauce, pulse in more olive oil, up to ½ cup total.

Taste and adjust the salt, pepper, and lemon juice. Transfer the chimichurri to a bowl or jar and set it aside so the flavors can meld while you grill the vegetables.

Heat a charcoal or gas grill to medium to medium-high heat, about 400°F to 450°F. Scrub the grates clean and brush them lightly with oil.

In a small bowl, stir together the chili powder, cumin, smoked paprika, and a generous pinch of salt and pepper.

Brush the eggplant, bell peppers, zucchini, and corn all over with olive oil, then sprinkle the spice mixture evenly over all sides.

Place the vegetables directly on the grill grates and cook until tender and charred in spots, flipping once halfway through and rotating the corn several times so it browns evenly. Plan on about 3 to 5 minutes per side for the eggplant and bell peppers, 4 to 6 minutes per side for the zucchini, and 10 to 15 minutes total for the corn. Transfer the vegetables to a platter as they finish and let them rest until cool enough to handle.

Chop the eggplant, bell peppers, and zucchini into 1-inch chunks. Stand each ear of corn on its end and slice the kernels off the cob with a sharp knife.

Warm the tortillas on the grill for about 20 seconds per side, or wrap them in a clean towel and microwave them for 30 seconds.

Spoon some of the grilled vegetables onto each warm tortilla, top with a few slices of avocado, and drizzle with chimichurri. Serve immediately, with extra chimichurri on the side.