Melt the butter in a pan.
Add the finely chopped onion into it and saute till brown.
Reduce the heat and add maida to it and stir well for 2 mins.
When a nice smell comes, slowly add the milk into it stirring constantly.
Mix well without forming any lumps.
Add salt, pepper, cream and celery to it.
:- If u do not like the flavour of celery, u can avoid that.
:- The paste should not be very thick, should be in medium consistency.
If needed, u can add mayonnaise or more cream to it.
:- To this mixture, you can also add chopped cucumber, carrots, beans, cabbages or tuna, boiled chicken etc.