Combine the smoked paprika, sugar, cumin, salt, and cayenne in a small bowl and set aside for seasoning the chickpeas.

Heat the larger portion of vegetable oil in a large skillet over medium-high heat until it shimmers but does not smoke. Carefully add the chickpeas and cook, stirring occasionally, until they are brown and very crisp, about 10 to 12 minutes.

Drain the chickpeas through a fine-mesh strainer into a heat-proof bowl. Transfer the hot chickpeas to a medium bowl and toss with the spice mixture until evenly coated, then lightly crush about 1/4 cup of them with a fork to help the seasoning and texture better integrate with the greens.

Adjust an oven rack to the highest position and heat the broiler. Toss the sliced red onion with the remaining tablespoon of vegetable oil on a rimmed baking sheet and broil until the edges are charred and the centers are softened, about 5 minutes.

Whisk the cider vinegar, mustard, honey, lemon zest, mayonnaise, and salt together in a large bowl. Slowly whisk in the olive oil until the dressing is emulsified and creamy.

Add the mesclun and charred onions to the dressing and toss gently to coat. Scatter the warm, spiced chickpeas over the top and serve immediately while the crunch is at its peak.