1 bunch baby white turnips with greens, such as Hokkaido (8 ounces)
4 tablespoons French-style unsalted butter
2 small red onions, diced
Kosher salt and black pepper
1 1/2 pounds fresh black-eyed peas in pods, shelled
Fresh mint leaves
Remove the green tops from the turnips, and cut the turnips into quarters or sixths depending on size. Separate leaves from stems and discard stems; wash leaves.
Melt 2 tablespoons butter in a 3- to 4-quart shallow stovetop braiser over medium heat. Sweat onion in butter for 1 minute, until translucent. Add turnips and sweat 2 minutes, until glossy and starting to “shine.”
Run a knife through the leaves once, maybe twice, and add to the pot. Season with a healthy pinch of salt and stir until leaves are also starting to sweat and wilt.
Add peas and 1 cup of water. Season with two large pinches of salt (restaurant-chef pinches, not home-cook pinches). Cover. Reduce heat. Simmer for approximately 10 minutes.
Stir. Add 1 cup water. Add pinch salt. Re-cover. Simmer for 10 more minutes.
Stir. Simmer for 10 to 15 more minutes, or until beans are cooked and soft and starchy inside, turnips are cooked and water has turned grayish purple. Taste for salt and season. Let cool completely on stovetop with heat off.
Cover and refrigerate overnight to allow everything to meld and settle. Serve the next day, reheated over low until tepid, stirring in remaining 2 tablespoons of butter to melt gently into the broth. Finish with a shower of fresh mint and ground black pepper.