Step 1

Mix pumpkin seeds, chives, lime zest, and lime juice into butter in a small bowl; season with salt and pepper. Transfer to parchment paper and roll into a log, or scrape into an airtight container; cover and chill.

Step 2

Do Ahead: Butter can be made 3 days ahead. Keep chilled.

Step 3

Prepare grill or campfire for medium-high heat. Lay out four 12" squares of heavy-duty foil. Divide potatoes and chorizo among squares; drizzle with olive oil and season with salt and pepper. Fold edges up and over to create packets; pinch edges closed. Cook on grill until potatoes are tender, 25–35 minutes.

Step 4

Heat vegetable oil in a large skillet on camp stove or stovetop over medium-high. Season cod with salt and pepper and cook until underside begins to brown, about 4 minutes. Turn; cook just until cooked through, about 2 minutes. Top with pumpkin seed butter. Open packets and top potatoes with cod; spoon any butter left in pan over.