Broccoli and Courgette Soup

Another request from my niece.

Ingredients:
Broccoli    400 gms       Florets cut in halves . Stalk can also be used ,remove hard bits.
Courgette  150 gms       Washed and cut into chunks.No need to peel.
( Or bottle gourd / Doodhi/Lauki in case Courgette is not available. Need to peel and dice.)
Onion          1 medium , peeled and chopped
Celery  greens or stalks      1/2 cup  washed and chopped
Olive Oil    1 tbsp. 
Salt to taste
Pepper powder to taste
Boiling water     3 mugs / 500 - 600 ml

1. In a heavy based pan , on a low heat, heat the oil. 
2. Toss in the onion. Stir.Cover and cook for 2 minutes till it softens.
3. Add the celery. Stir.Cover for 1 minute.
4. Add the broccoli and courgette. Increase the heat. Mix well.
5. Add the boiling water .Mix. 
6. Cover and cook for 8-10 minutes till the vegetables soften.
7. DO NOT OVERCOOK. Try to retain the green colour of the broccoli .
8. Blend with a hand mixer.
9. Add salt and pepper to taste.
10. If you think the soup is too thick, add some more water.