Prep and measure everything first. Having the quinoa fully cooled (refrigerated if possible) prevents it from steaming the other ingredients and turning the salad soggy. Rinse and drain the canned chickpeas thoroughly to remove excess sodium and canning liquid that can water down the dressing.

Pat the chickpeas dry on paper towels and, if you like a nuttier texture, spread them on a tray and roast at 400°F (200°C) for 10–12 minutes until they begin to brown slightly. This step is optional but toasting the chickpeas concentrates flavor and prevents them from becoming mushy in the salad.

Quarter the cherry tomatoes, dice the red bell pepper, finely dice the red onion (or slice scallion greens), dice the cucumbers and shave the corn from the cob. Cut the avocados and store them covered with a little lemon juice to slow browning. Keep the vegetables roughly the same size as the quinoa grains — this creates even texture and pretty presentation.

Make the smoky sumac yogurt: in a small bowl whisk the Greek yogurt with 1 tsp ground sumac and the smoked paprika. The sumac adds bright, lemony tang and the smoked paprika gives a warm background note — whisking them into the yogurt distributes those flavors evenly without adding extra oil. Taste and adjust: add a pinch of salt if needed.

Whisk the dressing: in a medium bowl combine the 4 tbsp extra‑virgin olive oil, 4 tbsp fresh lemon juice and the whole grain mustard (if using). Whisk until emulsified — this binds the oil and lemon so the dressing clings to quinoa and vegetables instead of pooling at the bottom.

Toss quinoa and dressing: place the cooled quinoa in a large mixing bowl and pour half the dressing over it. Toss gently with a rubber spatula to coat every grain — coating the quinoa first flavors its interior and prevents the salad from tasting dry. Taste for seasoning and add a little flaky salt and pepper.

Add vegetables and herbs: add the diced cucumber, corn kernels, cherry tomatoes, diced red pepper and diced red onion to the bowl with quinoa. Add the chopped parsley and chopped mint. Fold everything together gently — overmixing can bruise the herbs and release excessive water from the tomatoes; gentle folding preserves color and texture.

Add chickpeas and remaining dressing: fold in the drained (and roasted, if you decided to roast) chickpeas and drizzle the remaining dressing over the mixture. Toss once more to combine. The second addition of dressing adjusts final seasoning and keeps the salad bright without overdressing.

Plate and finish: divide the salad among 4 bowls or serve family‑style. Add 2 sliced avocado halves (one per person) or arrange sliced avocado on each portion. Spoon a dollop (about 1–2 tbsp) of smoky sumac yogurt alongside or on top of each serving and finish with a scattering of flaky sea salt and freshly cracked black pepper.

Rest briefly if you have time: let the assembled salad sit 10–15 minutes at room temperature to let flavors marry; the mint and parsley will infuse lemon and olive oil into the quinoa. If serving later, store refrigerated (covered) up to 24 hours and add avocado just before serving to prevent browning.