By Yewande Komolafe, The New York Times When I returned from Nigeria at the end of February, it was at the tail end of the Harmattan, a season when the winds from the north deposit the finest sand from the Sahara onto Lagos’ every surface. The city was hot and dry, and the markets were bursting with life. I’m not a vegetarian, but in Lagos, nutrient-dense produce surrounded me, inviting me to cook with it.