Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Zest and halve lime.

Toss potatoes on a foil-lined baking sheet with a large drizzle of oil, half the Cajun Spice Blend (you’ll use the rest in Step 4), salt, and pepper.

Roast on top rack until browned and tender, 20-25 minutes.

Meanwhile, in a medium bowl, combine coleslaw mix, 1 tsp sugar (2 tsp for 4 servings), juice from half the lime, salt, and pepper.

In a small bowl, combine mayonnaise and as much lime zest as you like.

Refrigerate slaw and lime mayo until ready to use in Step 7.

In a large bowl, whisk together tempura batter mix, remaining Cajun Spice Blend, ½ cup cold water, and ½ tsp salt until smooth (⅔ cup water and 1 tsp salt for 4 servings). TIP: If mixture is too thick, add more cold water 1 TBSP at a time until it reaches a pancake-batter-like consistency.

Pat tilapia* dry with paper towels. Season all over with salt and pepper. Add tilapia to bowl with batter; gently turn until evenly coated.

Heat a ¼-inch layer of oil in a large, heavy-bottomed pan over medium-high heat. Once oil is hot enough that a drop of batter sizzles when added to the pan, add tilapia in a single layer. (Shake off excess batter before adding.)

Cook until golden brown and cooked through, 2-3 minutes per side. TIP: To check for doneness, cut one fillet in half. (For 4 servings, fry fish in batches, adding more oil as needed and allowing oil to get hot in between batches.)

Using tongs or a slotted spoon, transfer to a paper-towel-lined plate. Immediately season with salt and pepper.

While tilapia cooks, halve baguettes lengthwise and toast until golden.

Spread cut sides of baguette halves with as much lime mayo as you like; fill with tilapia and slaw.

Divide sandwiches between plates; serve with potato wedges and any remaining lime mayo on the side for dipping.