Anybody know what might work to correct the bitterness I got from Blendtec blending fresh tomatoes, onion, jalapeño, cilantro, and garlic salsa?
If the problem is just a little bitterness on the tongue, salt is usually the best foil. If you can find out where the bitterness came from by sampling other pieces of your raw ingredients, you can try upping the ratio of other ingredients to temper it.
Advice more specific than that would require a crystal ball, I'm afraid. If it's really quite noticeable, then you're probably better off making a new batch with new ingredients.
My guess would probably be the garlic, if it's a fresh salsa. That's going to impart a certain amount of bitterness if everything is left raw.
A couple suggestions (I'm just spit-balling here) - maybe roast the garlic and add roasted garlic paste, instead of raw garlic (also, garlic carries botulism bacteria, which is why it is not recommended that people make homemade garlic-infused oils).
Another might be to leave out the garlic altogether. People rave about my fresh salsa, and it's just cilantro, lime juice, salt, jalapeno, sweet onion and tomato.
Assuming that's all fresh raw ingredient, don't blend it, chunk it.
You have almost all the ingredients for a classic pico di gallo there - which isn't traditionally blended, it's left in small cubes/chunks.
If it tastes better, then you were probably over-blending seeds from either the tomatoes or chillies.
If it still tastes bitter, change your supplier.
I'd also squeeze half a lime into that mixture & a good hit of salt too, which will either just give some zing if you eat it now, or help soften the textures & mellow the flavours after a few hours.
Ratios for pico di gallo would be approx
1 clove garlic
cilantro [coriander] …'a small bunch' - kind of hard to weigh or otherwise accurately measure. I work by sight, add until the 'colours weigh the same' [red against green against white] not the actual quantities.
salt 'to taste' - no-one can gauge this for you, but I find people tend to under-salt things these days because they think it will kill them ;)