How to Make It
In a large saucepan, heat the olive oil until shimmering. Add the onion and garlic and cook over moderately low heat, stirring frequently, until the onion is softened, about 3 minutes. Add the stock, white wine, tarragon, sherry vinegar, honey and thyme and bring to a boil over high heat. Reduce the heat to moderately low and simmer for 10 minutes. Strain the broth through a fine sieve, pressing hard on the onion to extract as much liquid as possible.
Preheat the oven to 400°. On a lightly floured surface, roll out the chilled puff pastry 1/8 inch thick. Using a 6-inch bowl or plate as a template, cut out 6 rounds. Use a sharp knife to cut a 1-inch long slit in the center of each circle, then carefully transfer the puff pastry rounds to a large baking sheet and refrigerate them until well chilled.
Melt 2 tablespoons of the butter in a large, deep skillet. Add the potatoes and carrots and cook over moderate heat until softened, about 10 minutes. Add the asparagus and morels, season with salt and pepper and cook over moderately high heat, stirring frequently, until the asparagus is crisp-tender, about 3 minutes. Add the scallions and cook, stirring, for 2 minutes. Add the kale and cook, stirring frequently, until wilted, about 2 minutes longer. Stir in the peas and cook just until heated through. Season the vegetables with salt and pepper and transfer to a large bowl. Stir in the snipped chives and chopped parsley.
Return the skillet to moderate heat and melt the remaining 3 tablespoons of butter. Add the flour and cook, stirring, until pale golden, about 1 minute. Whisk in the strained vegetable broth and cook over moderately high heat, whisking constantly, until thickened, about 2 minutes. Whisk in the cream and mustard and season with salt and pepper. Stir the vegetables into the sauce and let cool slightly.
Spoon the vegetable filling into six 1 1/4-cup ovenproof bowls. Lightly brush the rim of each bowl with the egg wash and carefully top each bowl with a puff pastry round. Gently press the pastry around the edges of the bowls to seal. Brush the pastry with the egg wash and set the bowls on a large rimmed baking sheet. Bake the potpies for 30 minutes, or until the tops are golden brown and puffed and the filling is bubbling. Serve at once.
One ounce of dried morels can be substituted if fresh morels are unavailable. Soak the dried mushrooms in 1 cup of boiling water until thoroughly softened; drain.