Given the background description of some cooking related query, summarize the question into a title

Q: Can I use sprouting vegetables? Are they poisonous? When cooked, does the sprouting have an effect to foods taste?Can I use my potatoes or carrots if they already has some roots...?How about when my onion is sprouting?

A: Are vegetables poisonous if they have roots, are sprouting or are many weeks old?
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Q: I've read somewere in the net that sushi is an extremely difficult food to prepare. It will take at least one year just to learn to cook the rice, and ten year to complete the experience.It's so difficult? To do a comparison, one could prepare a decent home sushi like one can prepare a decent home dish after some years of home cooking?It's more like a western chef that needs anyway to study and practice for a long time?

A: Is sushi so difficult?
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Q: I have experience making a roux with butter and flour. If I want to substitute a non-dairy fat (e.g. olive or sunflower oil), will there be any cooking or consistency differences that I need to watch out for? Does the fat/flour ratio stay consistent?

A:
Is an oil-based roux cooked the same as one made with butter?
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