How to Make It
Set the leeks cut side up in a large skillet. Add the stock, butter, bay leaf, thyme sprig and a pinch of salt. Cover tightly and simmer over low heat until tender, about 30 minutes. Using a slotted spoon, transfer the leeks to a platter and drizzle with 2 tablespoons of the cooking liquid. Let cool completely.
In a medium bowl, whisk the mustard with the chopped thyme, lemon juice and vinegar. Gradually whisk in the olive oil and season with salt. Scatter the feta over the leeks and drizzle lightly with some of the dressing. Add the persimmons and arugula to the remaining dressing in the bowl, season lightly with salt and toss. Mound the salad over the leeks, garnish with the almonds and serve.