1- Fill a saucepan half full with water and bring to a boil. Add green beans and fennel slices; cook until just beginning to become tender, about 4 minutes. Pour into a colander to drain and run under cold water to stop the cooking process.
2- Return the empty pan to the stove and set heat to medium. Pour in the olive oil and it heat for a minute. Return the green beans and fennel to the pan. Season with basil, salt, and pepper, cook and stir until coated and warm.
3- Transfer to a serving dish and toss with feta cheese.