Combine the paprika, sugar, cumin, salt, and cayenne in a large bowl. Heat the oil in a large Dutch oven over high heat until it just begins to smoke—the oil should shimmer and show small wisps of smoke.

Carefully add the chickpeas and partially cover the pot to prevent splattering. Fry, stirring occasionally, until they are deep golden brown and shatteringly crisp, about 10 to 12 minutes.

Transfer the chickpeas to a paper towel–lined plate using a slotted spoon to drain briefly. Toss them in the bowl with the spices while still warm, then use a fork to crush about half of the chickpeas into coarse crumbs.

Set an oven rack 6 inches from the broiler element and heat the broiler. Toss the onion with oil and salt on a foil-lined rimmed baking sheet and spread into an even layer. Broil until the edges are charred and the centers are softened, 6 to 8 minutes, stirring halfway through.

Whisk the vinegar, mustard, honey, lemon zest, mayonnaise, and salt in a separate bowl. Drizzle in the oil while whisking constantly until the dressing is thick and creamy.

Add the charred onions and mesclun to the spiced chickpeas. Pour the dressing over the top and toss until the greens are well-coated and the crushed chickpea bits cling to the leaves. Serve immediately while the whole chickpeas are still at their peak crunch.