Fish & Chips

Ingredients:
4-6oz cod fillets, rinsed and patted dry with paper towels
½ cup self rising flour, divided
6 Tbsp cornstarch or potato starch
1 tsp baking powder
1/2 tsp curry powder
1/2 tsp smoked paprika
1/4 tsp garlic powder
1/2 tsp salt
1/2 tsp cracked black pepper
⅔ cup club soda

2 lbs potatoes (Yukon gold or russets work best here)
1 qt oil for frying

¼ cup crème fraiche or sour cream
2 Tbsp mayonnaise
1 tsp Dijon mustard
1 Tbsp capers, roughly chopped
2 Tbsp dill pickles, chopped
1 tsp dried dill
1 tsp cayenne pepper or hot sauce, plus more to taste
1 lemon, halved
½ tsp salt