Bengali Green Beans with Mustard Seed and Almonds

1 pound green beans, broken into 1 1/2-inch pieces
1/4 teaspoon salt
1 Tablespoon vegetable oil
1/4 teaspoon kalonji (nigella) seeds
1 teaspoon brown mustard seeds
1/4 medium onion, peeled and sliced
3 cloves garlic, peeled and minced
1/4 teaspoon cayenne
1/2 teaspoon turmeric
Juice of 1/2 lemon
1/4 teaspoon black pepper, freshly ground
salt to taste

Garnish:
3 Tablespoons blanched slivered almonds, toasted and coarsely chopped

Fill a large pot with enough water to cover the beans and bring to a boil. Add the beans and 1/4 teaspoon salt. Boil for 3 minutes. Drain and set aside.
In a large skillet, heat the oil over medium-high heat. Add the kalonji and mustard seeds, stir until they begin to pop, about 30 seconds. Add the onion and saute until it begins to brown, about 3-4 minutes.
Add the garlic and cook another 2 minutes. Add the cayenne and turmeric, stir a few times, add the green beans and lemon juice. Stir and cook until the beans are heated through, about 2 minutes. Stir in the black pepper and salt to taste.
Serve garnished with almonds.