It was like a scene from one of those wartime espionage movies. No sooner had I lifted the seemingly innocuous package from the shelf of my local deli, than I felt the cold slap of a recriminatory hand on my shoulder.
In tones of sotto voce urgency, the owner of said arm hissed in my ear. "That stuff is much cheaper at the supermarket".
Welcome to the world of the hard-pressed, pre-Pesach shopper. A time when so many of us go like (pascal) lambs to the slaughter because of mercenary kosher food outlets who knuckle us with the soaring cost of celebrating Passover.
Every year, you can barely hear yourself for the ear-bothering ker-ching of the tills as local delis and food shops enjoy the liberating cash bonanza that marks our freedom from slavery.
Yes, business is business. And before proprietors start wailing 10 bars of "we're entitled to make a living," I understand that successful commerce is about maximising an opportunity. (It astonishes me that Kate Middleton's parents aren't offering pop-up Seder plates on their Party Pieces website.)
But there is something that sticks in the craw about the manifest, eye-watering expense of being charged a Pharaoh's ransom at Pesach time.
It's especially unpalatable when the United Synagogue sends out letters of appeal to its members, asking them to assist financially with the ever increasing cost of providing the kosher l'Pesach food packages that enable needy Jewish families to celebrate the holiday in traditional fashion.
For, while we are being prevailed upon to help those vulnerable members of our community, the kosher shops - from whom the US purchase the groceries - are the ones who benefit from this bonanza. Is it really in the spirit of Pesach, a time of celebrating our liberation, for local Jewish businesses to see Yomtov as a God-given opportunity to arm-lock us this way?
Let's be clear: we must, if we can, help the weak and vulnerable among us - particularly if it means the difference between having kosher Pesach food or not. But, at times of austerity, it becomes increasingly challenging for some to do this because of the huge mark-up in so much of the kosher l'Pesach food sold in local outlets.
I have no desire to see local businesses close because they can't compete with supermarkets. But it is the supermarkets who are offering some redemption by lowering prices on some lines. Only the other day, I paid 40p for a box of matzah in my local Morrisons.
So before the local shops start marking up those cans of Passover crushed tomatoes, they should think hard about whether they are offering customers more choice or sending them away.
Ironically, if you look at the labelling, many products are now kosher for Pesach all year round. So why charge so much more, since the argument about extra supervision clearly doesn't hold water.
The drawback is that the big supermarket chains do not have the space or the desire to offer the enormous range of products that are now available at Pesach (Suppliers must assume that we will collapse as a community if we cannot enjoy every delicacy under the sun on our matzah). And ask some supermarket staff if they stock kosher l'Pesach chicken shmaltz and they either look at you with blank incomprehension or think you're propositioning them in Romanian.
So if the US wants us to help the needy, perhaps it's time the organisation had a word in the shell-likes of those who sell astonishingly overpriced Pesach food.
Otherwise, hopefully, canny supermarkets will start offering even more choice of Passover goodies, using their ability to buy in bulk to keep prices down. Meanwhile, I'm off there now to do some shopping and a trolley-dashing mitzvah. After all, every little helps.