"I was asked to help out by a friend in the department of economic affairs," said Mr Tesfamariam, who has an office at the headquarters of the ruling People's Front for Democracy and Justice. "I was a fundraiser for the struggle while I was in London. Even though it meant leaving my family behind, I felt I had a sense of duty to come back for a few years. People like me can be of great assistance because we're starting from scratch."
His commitment is typical of the selflessness which characterises so many Eritreans. He is working without pay to help realise a vision that more than 100,000 of his fellow countrymen have already paid for with their lives. Countless thousands of fighters were disabled and nearly half a million people fled during the war. The impact of such losses on a country the size of England with only 3 million people, is not hard to imagine.
Most government employees perform two or three jobs. Everywhere you go, people are busy building, repairing. Dr Berekt Habte Selassie, chairman of the commission drafting a new constitution, said there was "an almost demonic determination to get things done". Eritrea, one of the poorest countries in the world with an annual per capita income of only pounds 100, is being seen as a model for the regeneration of a whole continent.
Glenn Anders of Usaid, the United States development agency which has made Eritrea its biggest per capita aid recipient on the continent, said: "This country could be one of the success stories. The national sense of purpose, the discipline of its people, the hard work which is evident in the countryside ... give us cause for hope."
The rock-filled dam being built at Hayelu, a highland farming community not far from the capital, is an example of the infrastructural investment favoured by the government. Rather than using expensive or imported materials, the agriculture ministry is relying on local stone and labour.
In the end, there is something disconcerting, even faintly disturbing about the self-reliance of the Eritreans. The government has already turned down pounds 30m funding from the International Monetary Fund because of reluctance to accept certain policy reforms. It has likewise rejected 100,000 tons of wheat from the European Union because of the pricing conditions attached to the offer.
These are people who want to make their own mistakes and who will not be dictated to by outsiders. For the moment, Eritrea is united by a sense of common purpose. Five years after victory and two years after a referendum which endorsed independence, hundreds of disabled fighters are still living in Asmara's Denden camp. They receive less than pounds 1 per week pocket money. Yet no one complains and no one suggests that their sacrifices might not have been worth it.
It remains to be seen whether this national consensus can survive the social and economic difficulties generated by reconstruction. Plans to develop tourism, marine resources and mining are as yet far from realisation.
If rewards are not forthcoming by next year's elections, the ruling party might find that goodwill is not enough when people go hungry.