ABC Soup (chicken/ pork bones base) ABC 汤

I cook soup for my son everyday, chicken or pork bones based with fresh ingredients. I called this ABC soup because my mom named it ABC soup. But my son didn't like the name, he named it 'IJKL soup' ... the reason is....' because.... he likes to drink IJKL soup!' lol...

Ingredients: (yield 2-3 servings)
1 Chicken Bones or 250g Pork Bones
3 Medium Size Carrots
2 Potatoes
3 Small Onions
1 Ripe Tomato
Sea Salt

Method:
1. Rinse the bones with boiling water.
2. Put all ingredients into a pot (except tomato). 
3. Add 1.5litre boiling water.
4. Cook with high heat for 30 minutes.
5. Cook with low heat for 60 minutes.
6. Add salt and tomato. Cook another 30 minutes.