green papaya salad using a piece of fruit we'd bought at our beloved giant Asian market, but realized when we cut into it that it wasn't a papaya but a mango! In our haste, we'd grabbed the wrong kind of fruit without noticing.
What to do? We'd never used a green mango before. Consulting the Internet, we discovered that you can make a Thai green mango salad. Fine. But we were also out of limes and basil, two key ingredients. And our bean sprouts were in sorry shape.
We could have scrapped the whole idea of making a salad, but we'd already cut into the mango and didn't want to waste it. So we looked more closely at the recipe.
We had plenty of lemons; why not use them for the salad dressing? And our garden was rapidly filling up with mint, a close cousin of basil. We decided to substitute.
The resulting salad was delicious. Sure, lime would have been more authentically Thai, but the lemon juice was perfectly acceptable. Mint provided a flavor that was more Vietnamese than Thai, but that was fine with us. Bean sprouts would have added a nice crunch, but the salad worked fine without them.
The lesson: never be afraid to substitute. You may not end up with the exact recipe you're looking at, but you will probably end up with something pretty damn good.