Step 1

Cook wild rice in a medium pot of boiling salted water until tender and grains start to split, 35–40 minutes. Drain; let cool.

Step 2

Meanwhile, combine basmati rice, lime, if using, and 1½ cups water in a medium saucepan, season with salt, and bring to a boil. Reduce heat, cover, and simmer 10 minutes. Remove from heat and fluff with a fork. Cover; let sit until water is absorbed, about 5 minutes. Let cool; discard lime.

Step 3

If using fresh fava beans, cook in a large saucepan of boiling salted water until tender, about 4 minutes. Drain; transfer to a bowl of ice water. Drain and peel. (If using frozen fava beans, cook 2 minutes; transfer to a bowl of ice water, then drain.)

Step 4

Toss wild rice, basmati rice, dill, parsley, pistachios, oil, lemon zest and juice, lime powder, and fava beans in a large bowl; season with salt.

Step 5

DO AHEAD: Fava beans can be cooked and peeled 2 days ahead; cover and chill. Wild and basmati rice can be cooked 2 days ahead; cover and chill.