Question:
On the nine days when one would not eat meat, is it permitted to eat an onion that has been cut with a (clean) meaty knife?
Answer:
The prohibition not to eat meat only applies to the actual meat or its gravy, but not to taste that was absorbed into a pot or a knife. Therefore you may pareve food cooked in a meaty pot or an onion cut with a meaty knife.
Sources:
Mahari Bruna 13, Eliyahu Rabba 551-22, M:B 551-63.
