Drain and rinse the chickpeas well, then let them dry off as much as possible. Halve the cherry tomatoes, dice the cucumber, and slice the red onion thinly. Chop the parsley and mint. Add the chickpeas, tomatoes, cucumber, red onion, parsley, and mint to a large bowl. Do not leave the chickpeas wet from rinsing. Excess surface water dilutes the dressing and makes the salad taste flat rather than bright. Any residual surface moisture clinging to the chickpeas would work against the dressing's own concentrated flavour the moment they meet, diluting it right at the point of contact.

In a small bowl or jar, combine the olive oil, lemon juice, lemon zest, Dijon if using, salt, black pepper, and garlic if using. Whisk or shake until emulsified. Taste it. It should be vivid, lemony, and slightly sharper than seems necessary on its own — once it coats the chickpeas and vegetables, the flavour will settle into balance. That deliberate over-brightness accounts for real, predictable dilution — a dressing that tastes perfectly balanced on its own would read as noticeably flatter once spread across this many other components.

Pour most of the dressing over the chickpea mixture and toss thoroughly. Reserve a small amount for finishing after the halloumi is added. Let the salad sit for 5–10 minutes while you cook the halloumi. This short rest is useful. Chickpeas benefit from a few minutes in the dressing so they absorb flavour, but do not let the salad sit too long before serving or the tomatoes and cucumber will start releasing too much water. That specific, brief window balances two competing needs — enough time for the chickpeas to genuinely absorb the dressing, but not so long that the vegetables' own moisture begins working against that same dressing's concentration.

Cut the halloumi into 8 slices, roughly 1.5cm thick. Pat the slices dry very well with paper towel, then brush lightly with olive oil. Drying the halloumi matters. A wet surface steams instead of sears and makes it harder to get strong golden grill marks. Any residual surface moisture on the halloumi converts to steam the instant it meets the hot grill, and that steam is exactly what prevents the direct, sustained contact real grill marks depend on.

Heat a grill pan, cast iron skillet, or outdoor grill over medium-high to high heat. Once properly hot, grill the halloumi slices for about 1–2 minutes per side until deeply golden with distinct grill marks. Do not move them around too early — let the crust form before turning. Remove as soon as both sides are browned. Halloumi should be cooked hot and fast. Overcooking makes it firmer and chewier than necessary, while a short hard sear keeps the interior pleasantly tender. Leaving the halloumi genuinely undisturbed during that initial window gives it the sustained, direct contact real grill marks require — moving it too early interrupts that contact before the crust has any real chance to form.

Transfer the dressed chickpea salad to a large serving bowl or divide among plates. Arrange the grilled halloumi slices over the top. Drizzle with the remaining dressing and finish with a little black pepper plus a few extra parsley and mint leaves if desired. Reserving a portion of the dressing specifically for this final drizzle, rather than using it all in the initial toss, gives the warm halloumi its own fresh coating right at the surface where it's tasted first.

Serve immediately while the halloumi is still warm and the salad is still crisp. Halloumi's own supple, warm texture changes noticeably as it cools, firming up into something considerably less pleasant to eat — serving without delay is what actually delivers the dish at its best.