Peel the potatoes and place in a large pot filled with water. Add eggs and bring to a boil. Eggs will take about 15 minutes after the boiling point to be very hard, so you can take them out at that time and place in a bowl with cool water. Time varies for the potatoes, so check them with a fork every few minutes. When they're soft, but not overly soft, they're ready to be taken out. Place in a bowl with eggs to cool.
Peel the eggs and cut into thin rounds the thickness of three pennies. Cut the potatoes up the same way. Chop up the onion. Combine all three, add spices, and let it rest for a minute.
Prepare the vinaigrette by combining all ingredients and stirring. Pour over eggs, potatoes and onion and mix well. Place the salad in the fridge.
If you bought the whole fish, clean it up by cutting in half perpendicularly, and taking the insides out. Wash the fish, and discard the insides together with the head and tale, but leave the skin on. You should be left with fish fillets. (If you had the fillets to start with you're good to go.)
Heat oil on high in a deep skillet until it's really hot. Pour flour on a plate evenly.
Dip each fillet in the flour and place in the skillet. Lower temperature just a little bit. Fry the first side for about 4-5 minutes. Flip and fry another 3-4 minutes. Place on a paper towel to soak up the extra oil.
Serve with potato salad. For best taste, squeeze more lemon juice over the fish.