In a large pot, combine 2 qt of water with catfish bones, bring to boil then simmer for 30 minutes. Discard the bones, strain the soup through a fine-mesh sieves. Return the soup to cooking pot, add tamarind soup base and Thai chilies. Bring to boil, then add fish sauce and sugar, stir occasionally. Adjust the taste accordingly using extra salt and sugar (if needed).
Let the soup pot simmer on medium heat, add the shrimp, pineapples, tomatoes, and cook for another 2 minutes or until the shrimps just turn pink.
Set up another small pot filled with water, bring to boil. When you're ready to eat, cook the veggies separately in this pot. Do not put the veggies directly in the soup pot because they might lose their freshness, original color, and nutrition.
For fried garlic: in a small saucepan, heat the oil together with garlic over medium heat. Stir frequently to prevent garlic from burning for about 5-8 minutes. Strain through a fine-mesh sieve, reserving the oil for later use. Let the garlic cool down then store in a air tight container.
When you're ready to eat: in a big soup bowl, put all cooked veggies in first, then add the shrimp, tomatoes, and pineapples together with hot & sour soup to the bowl. Topped with fried garlic and rice paddy herb. Enjoy!