Tom Yum Goon and Tom Yum Gai

1-2 liters of prawn stock or chicken stock prepare day before, or buy stock cubes 
8-12 fresh large shrimps (prawns), exoskeleton and intestinal tract removed
2-3 stalks of lemongrass
3-5 kaffir lime leaves (dry or frozen)
3-4 thick slices of galangal or pastе
Juice from 1-3 green limes, with more at the end
8-12 straw mushrooms, fresh once is best or canned or parboiled 
5-8 sherry tomatoes cut in half  
2-3 Ts of Tom yum goon paste( hot or medium spicy )
2 tsp thai brown sugar,(optional) 
2 tbsp thai fish sauce
pinch of salt to taste
generous sprig of coriander leaves.
Boil the stock,add limongrass kaffir leaves and galangal for (2-4 minutes ) and tomatoes with mushrooms, end shrimps until they turn to pink color not more 3 minutes, turn off the stove and add coriander leave and lime juice. 
For the chicken Tom Yum Gai

Follow the recipe above just instead of shrimps add chicken, before turn off stove add coconut milk or cream and coriander leave,lime juice.