1. While you drain the potatoes and carrots, set aside water. In the reserved potato-carrot water, dissolve the bullion. Put aside.
2. In 1 tablespoon of vegan butter or olive oil, sauté the leeks, garlic, and fennel until they are just translucent.
3. Put the asparagus in a cup and mix it perfectly while it combines properly.
4. Mix the blanched vegetables into the sauté. Heat the butter from the center and push to the pan’s edges. Whisk in the flour.
5. Stir the nut milk and the saved potato and carrot water into the bullion mixture.
6. Throughout the process, use a spoon to stir instead of a whisk. Add the pepper and mustard, then add salt to it.
7. When the sauce is squeezed, set it aside for a few moments to cool.
8. Switch off the heating source.
9. Stir in the chives, lemon juice, lemon thyme, and tarragon. Salt should be adjusted based on taste.
10. While you make the puff pastry top crust, let the filling chill.
11. Pinch out some puff pastry sheets if necessary. Cut to fit your pan, then place on top of the filling that has cooled. Because the pastry may shrink somewhat during baking, roll it out a few inches larger for a complete covering.
12. Using a sharp knife, score the pastry by slicing halfway through the dough and leaving a vent hole in the middle.
13. Create whatever kind of design you desire. Because of the lightening effect, the crust bakes more uniformly and rises more.
14. Use an egg wash if you’re not vegan, or brush with olive oil.
15. The crust should be golden and fluffy after twenty minutes of baking at 400 degrees Fahrenheit.

Notes:

• Should you neglect to defrost your puff pastry beforehand, you may thaw it in the microwave for a few seconds at a time, flipping it over, until it becomes soft and effortlessly unrolls. To firm it up, if you overshoot, and it becomes too soft, place it in the refrigerator for a little while. You want it slightly thawed but not heated.