This is something that happens to me, occasionally. It’s born of Hunky Husband telling me things aren’t that spicy, and possibly me overcompensating when I’m not cooking for children. I sometimes, perhaps, get a tiny bit carried away.
I’m basing these tips on a chilli, because that’s where my main problem lies. For other recipes, some of these tips may not be quite right (cheese in a curry?!) but by all means give them a go!
Mayonnaise or Sour Cream. These does alter the flavour somewhat, so if you don’t like mayo, give it a miss. I personally think a bit dollop of mayo in a chilli works quite well. Condiment based coolers and handy, because each person can mix in their own as required. Not as good if you’re trying to hide the fact that you did it wrong in the first place.
Add more of any non-spicy ingredients. In the case of a chilli, an extra tin of chopped tomatoes. Anything you can add to dilute the spice.
Cheese, the most wonderful thing on earth. Tastes great, and you can claim it’s meant to be cheesy. Other dairy works great too. You’ve heard the advice to drink milk when you eat a curry. It really does help. Dairy also doesn’t change your flavour too much. Naturally yogurt, cream or even milk can help a lot.
Apparently sugar works against the spicy to neutralize it. To be honest, I haven’t found this much use. Possibly because I make things that spicy you’d need 1kg of sugar to help. If it’s a tomato based dish, I recommend tomato ketchup. There’s lots of sugar in it, and it won’t affect your taste that much.
Another that neutralizes the spice. Lemon juice is a good option. Or vinegar. Again, would probably only work if it’s a small reduction of spice you’re after.
With any of these, add a bit at a time, and taste first! If you’re adding before serving, add a bit, stir, leave to simmer for a few minutes, then taste before adding more. Possibly consider doing this when you add the spicy ingredients in the first place!