Avocados, as assiduous readers of health sections and nutritional charts will know, are among the healthiest foods on the market. They are richer in phytochemicals than any other fruit. They contain lutein, which protects against prostate cancer and cataracts. They have nearly twice as much vitamin E content as scientists previously believed. And they've got loads of beta-sitosterol, which lowers cholesterol levels.
Once a bit naff, avocados are back, achingly hip and healthy. They are what the sun-dried tomato was in the 1980s or radicchio was in the 1990s. They are the "must eat" fruit, in salads in posh restaurants, in sandwiches at delis, or as a retro starter with prawns.
But there is a problem for those whose hipness extends to politics as well as diet. The avocado you just ate or bought could well have come from an illegal settlement in the Israeli-occupied West Bank.
According to the latest figures, Israeli avocado exports are up by almost 100 per cent, almost all of them ending up in European supermarkets. But the consumer has no way of telling whether they've come from undisputed land in Israel proper or from any of the many settlements on the West Bank or the Gaza strip. The latter, with the help of Israeli troops, have created a flourishing microeconomy next to Palestinian farms that have been bulldozed or left to waste so that the settlements may be "safe" and "secure". Agricultural exports are their mainstay, and it is high-tech, high-intensity farming.
Avocados are not the only crop at issue. The cherry tomatoes, vine tomatoes, strawberries, mange-tout, oranges and grapefruit in the supermarkets may also have come from the settlements. They will simply be labelled "made in Israel" or "product of Israel". And, in a manner of speaking, they are. Many Israelis refuse to recognise a distinction. The fruit and vegetables are taken by armed convoy along the highways to processing or packaging plants, and sent on from there. The export companies are registered in Israel.
"I don't know if any of our avocados come from the Jewish settlements," said a Tesco spokesman, who called back swiftly to assert that he thought they didn't. "It wouldn't be a political decision," was the intriguing comment from Safeway. Sainsbury's suggested that the Israeli avocado season is about to end and that it will switch to suppliers from other countries. A spokesman said "the main area" of avocado purchasing from Israel was in the north, along the coast.
Whatever their views on suicide bombers and Israeli military responses, many people, while happy to buy Israeli products generally, might baulk at doing anything to support the settlements. But according to Diane Langford of the Palestine Solidarity Campaign, there is no way of differentiating. "They [the export companies] label everything as made in Israel and often mix products like avocados with some that come from within the green line and some that come from the settlements," she says.
"What's happened is that they're supposed to give a certificate of origin. So it should really be traced back at the point of entry, and that's not happening. They're more or less turning a blind eye to that."
The Israelis have been even cleverer. They have identified a profitable and growing niche in the European market - organic products. So, as consumers place their pesticide-free bundle in their baskets, they will be telling themselves that they are making a political gesture. But it might not be the one they intended.