Toast the almonds one of two ways: either bake them for 3 minutes at 325 degrees or heat a large skillet over medium heat and cook almonds, stirring occasionally, until toasted. Set aside.
Heat a large skillet over medium heat, then add green beans, water, and 1/4 tsp. salt. Cover and cook 7-10 minutes, stirring periodically. Uncover and increase heat to medium-high. Continue to cook another 3-5 minutes or until water has evaporated and beans are crisp-tender and bright green. Remove from heat.
Meanwhile, make the dressing: whisk together olive oil, dijon, lemon juice, garlic, red pepper flaked, and black pepper.
When beans are done cooking, toss with toasted almonds, lemon dressing, and half the feta. Spread on a platter or serving dish and sprinkle with remaining feta. Serve immediately.