Chop the green beans into 2 or 3 equal pieces each. Place in a wide pan and add water with 1/2 teaspoon salt to cover the beans. Cover with a lid and bring it to a boil. Once it starts boiling, remove from heat and drain.
Prepare the dressing
Mix together wholegrain mustard, minced garlic, chili flakes, lemon juice and zest, olive oil and 1/2 teaspoon salt. Toss with the drained beans. Let it sit for 5 minutes before serving.
Notes
Chopping the green beans allows the mustard dressing to be absorbed well.
Boil the beans in salted water to enhance the flavor.
Toasted slivered almonds can be sprinkled before serving.