In a bowl, place the sugar, warm water and yeast, lightly mix and leave for 4-5 minutes, or until the mixture begins to foam.
Sift the flour, black pepper and baking powder into the bowl and mix together until well combined.
Add the milk, spring onion, hot pepper sauce, coriander, egg and thyme. Add salt to taste, then mix until smooth and cover with cling film. Leave for two hours, or until risen.
Add the cooked salmon and smoked salmon to the dough, mixing gently to combine. With damp hands, take small pieces of the mixture and roll into portions the size of golf balls.
Half-fill a deep, heavy-based pan with vegetable oil and heat until the temperature of the oil reaches 180C/355F, checking with a digital thermometer (CAUTION: hot oil can be dangerous. Do not leave unattended.) Fry the salmon balls in small batches, for 2-3 minutes each time, or until the salmon balls are golden-brown and crisp. Remove with a slotted spoon and drain on kitchen paper.
To serve, place the fried salmon balls onto a serving plate and place a small dipping bowl of tomato salsa alongside.