Guardian: We turned off the main road to Awassa, talked our way past security guards and drove a mile across empty land before we found what will soon be Ethiopia’s largest greenhouse. Nestling below an escarpment of the Rift Valley, the development is far from finished, but the plastic and steel structure already stretches over 20 hectares – the size of 20 football pitches. The farm manager shows us millions of tomatoes, peppers and other vegetables being grown in 500m rows in computer …