You can lessen the effect of an accidental excess of chilli by adding butter or ghee to your dish. It will not only lessen the chilli's effect but also improve the dish's flavour.
Sweeteners are a classic culinary trick for toned-down spice in a dish. You can use a little honey or sugar, or you can add sweet ketchup to enhance the flavour of the dish.
If the vegetable contains too much chilli, use fenugreek seeds to lessen its spiciness. Add the seeds to the vegetable after giving it a little fry.
To temper the spice and make the dish easier to eat, squeeze some lime or lemon juice or dilute it with a small amount of vinegar. This is great with creamy soups and chowders or seafood dishes.
Diluting spicy food is another easy method to temper it. This can be achieved by diluting a dish with water or by adding more of the non-spicy ingredients.