Preheat the oven to 425°F (220°C).
Prep the veggies for roasting. Chop the veggies: Wash and pat dry the eggplant, zucchini, and eggplant. First, slice the peppers, remove the seeds, and cut them into medium-sized pieces. Cut the eggplant in half and then into half-inch slices. Cut any big pieces in half again. Cut the zucchini in half and then into half-inch slices.Toss with oil, salt, and pepper: Toss the veggies with 2 tablespoons of oil and a pinch of salt and black pepper (about 1/2 tsp kosher salt or flaky sea salt and 1/4 tsp ground black pepper). Place them on a roasting tray (lined with parchment paper/baking paper for easier cleanup). Roast the vegetables. Place the roasting tray with the veggies on the middle rack and roast the veggies at 425°F (220°C) until tender on the inside and a little charred on the outside (about 30-35 minutes).
Cook the orzo pasta.Method 1: No draining required: Bring 3 cups of water to boil in a pot. Add the orzo and a pinch of salt and simmer until it’s cooked and all the water is absorbed (about 8-10 minutes). Stir from time to time to make sure the orzo pasta doesn’t stick to the bottom. This method makes for a creamier result but you have to be careful so the orzo doesn’t stick to the bottom of the pot.Method 2: Draning required: Bring a pot with at least 5 cups of water to a boil. Add 1/2 tsp salt and the orzo. Stir occasionally. Boil it until it’s tender (about 8 minutes) and then drain the excess water. This method is easier, but you lose some of the starch and creaminess. Add the pesto. Take the orzo off the heat and add the pesto to the orzo and stir so that it gets absorbed.
Add half the roasted vegetables, the lemon zest, the lemon juice, and salt & pepper. Stir in lemon zest, 2 tablespoons of lemon juice, and half the roasted vegetables (folding them into the orzo pasta gently so they keep their shape). Taste and add salt and pepper to your preference.
Plate up the orzo and add the remaining vegetables. Top the pesto orzo with the remaining roasted vegetables in the middle.