Dilled Alaska Cod Burgers With Avocado Spread

Name: 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