Source: Mangoes & Curry Leaves
[Instead of cayenne chilies I used a jalapeno pepper].
Cook the beans in a large pot of boiling salted water until just tender and still firm. Drain, refresh in cold water for a moment, and then drain again. Trim the beans on a diagonal into 1/2-inch lengths. Set aside in a bowl.
Heat a dry heavy skillet over medium-high heat. Add the sesame seeds, lower the heat to medium, and dry roast, stirring constantly with a wooden spoon, until lightly touched with gold and aromatic. Transfer to a spice/coffee grinder and grind to a coarse powder, then set aside.
Heat the oil in a small heavy skillet, a wok, or a karhai over medium-high heat. Toss in the chopped chilies and stir-fry for about 30 seconds, or until lightly touched with brown. Pour the chilies and hot oil over the beans and toss. Sprinkle on the ground sesame seeds and salt and toss. Add the lemon juice and toss.
Serve warm or at room temperature. If you wish, add chopped coriander or mint to the salad just before serving.