From India's perspective, New Zealand's desire for comprehensive agricultural liberalisation sits in the too hard basket.
But at multiple meetings in Auckland, Mehta said India could make a generous offer to New Zealand and move immediately to free trade in the services sector.
The top Indian trade official had probably taken the punt that with John Key scheduled to go to India for an official meeting with Indian Prime Minister Narendra Modi later this year, the prospect of being able to unveil a deal - or at least significant progress towards one - would have proved too tempting for Key to reject.
But as the prime minister made clear to Mehta, New Zealand is not after a piecemeal deal.
The negotiator's message flew directly contrary to New Zealand's free trade doctrine : High quality, comprehensive trade deals are the gold standard as far as the NZ Government and its trade negotiators are concerned.
That means agriculture must be included.
Mehta was officially in Auckland for the 13th round of negotiations on the Regional Comprehensive Economic Partnership (RCEP), a regional trade deal that includes the 10 Asean nations plus India, China, Japan, Korea, Australia and New Zealand.
RCEP is important to New Zealand because it brings India into the "noodle bowl" of free trade deals that New Zealand has been negotiating since the World Trade Organisation (WTO) talks stalled.
Mehta's presence was doubly important as far as NZ is concerned.
He kicked off the first round of negotiations on a bilateral free trade deal with New Zealand.
The talks are now into the 10th negotiating round - and after a period of absence working on the bigger game leading India's WTO positioning - Mehta recently picked up the NZ deal again.
At events hosted by the India New Zealand Business Council and another by the rival India Trade Alliance, Mehta made a compelling argument for India's positioning.
He said he had become frustrated by repeated calls from negotiating partners for India to lower its tariffs and also by the many complexities that had crept up in trade negotiations.
So he vented his frustrations to a "guru" - a former Commerce Ministry boss - who said high tariff barriers were now a thing of the past (including for India) after the impact of joining the WTO. India's trade intensity as a percentage of GDP is almost 50 per cent; higher that that of the US or China.
"But more important than that, some of our most dynamic trade is happening with countries with which we do not have free trade agreements.
"So the point this guru of mine is making is 'Don't be such a pessimist ... keep working but keep looking outside the trade negotiation box'."
Obviously, the FTA path could happen two ways: One through RCEP itself and then through a "RCEP Plus" agreement with New Zealand.
But Mehta's other compelling argument is the difficulty of getting progress in the Indian political system.
He said he was a "fanatical negotiator" ... "I know what is the best from one point of view but I also know what is possible."
There will have to be concessions all round if NZ is to notch this deal.