Boil 1 1/2 pounds green beans, 6 to 8 minutes. Drain and cool in ice water, then drain and dry. Toast 1 teaspoon ground cinnamon in a skillet with 2 teaspoons olive oil, 1 minute. Mix with 1/2 cup Greek yogurt and 1 teaspoon salt, then toss with the beans. Toss 2 sliced shallots in flour and fry in the skillet with more oil, 3 minutes; sprinkle on top of the beans.