There is a an Uncle Friendly at the Guillermo Gamera Way at lx, a vendor of food, who sells many useful stuff (like vegetables) by the low prices.
You can buy a rice for 4 currants and olive oil for 5 currants. Then you can make a Plain Noodles from 2 rice, and then Fried Noodles from one Plain Noodles and one Olive Oil and sell it to the same vendor for 20. Cost of components is 13, the profit is 7 (it's a bit smaller, cause when cooking you spending energy and eating Fried Noodles).
Result: infinite loop of getting lots of experience and profit just in one place.