Step 1

Preheat oven to 250°. Brush a large baking dish with oil. Combine chickpeas, cumin, and 1 Tbsp. oil in a medium bowl. Mash about half of chickpeas with a fork; season with salt and pepper. Transfer chickpea mixture to prepared dish.

Step 2

Heat remaining 1 Tbsp. oil in a large skillet over medium-high heat. Cook garlic, stirring, until fragrant, about 30 seconds. Add mustard greens and cook, tossing, until slightly wilted, about 1 minute. Add honey and ¼ cup water; season with salt and pepper. Cook, tossing, until greens are completely wilted, about 2 minutes. Transfer to dish with chickpea mixture.

Step 3

Season salmon with salt and pepper; arrange over greens and chickpea mixture and drizzle with oil. Bake until salmon is opaque in the center, 30–35 minutes.

Step 4

Whisk shallot, lemon juice, mustard, and honey in a small bowl; season with salt and pepper. Gradually whisk in olive oil; season with salt and pepper.

Step 5

Heat vegetable oil in a small saucepan over medium-high heat. Cook capers until opened and crisp, about 30 seconds; drain on paper towels.

Step 6

Drizzle salmon with vinaigrette and top with capers.