Dilled Alaska Cod Burgers With Avocado Spread

Ingredients

• 1 lemon, halved (use on half for the burger; cut remaining half in wedges)
• 1 small ripe avocado, peeled, pitted, and mashed
• 1/2 teaspoon garlic powder
• 1/4 teaspoon sriracha chili sauce, or more to taste
• 1/8 teaspoon salt and freshly ground pepper
• zest of half a lemon
• 2 tablespoons chopped fresh dill, (or 2 teaspoons dried dill)
• 1/4 teaspoon each, salt and freshly ground pepper
• 1 pound alaska cod fillets or pieces, fresh or thawed
• 1 tablespoon canola oil
• 4 toasted whole-wheat buns, or 4 butter lettuce leaves for wraps
• 1 cup baby arugula