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root vegetable mash knishes piled on plate.
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5 from 14 votes

Knish Recipe with Root Vegetable Mash

This knish recipe is a delicious root vegetable mash, wrapped and baked in a golden flaky puff pastry (store-bought). Melt-in-your-mouth and really easy. A great make ahead side dish or appetizer.
Prep Time10 minutes
Cook Time1 hour
Total Time1 hour 10 minutes
Course: Appetizer, Side Dish
Cuisine: American, Jewish
Servings (change as needed): 34 pieces approximately

Ingredients

For Root vegetable mash

  • 2 pounds root vegetables Note 1 (this will make a bit more than you need)
  • 2 tablespoon butter (or neutral oil) use 3 tbsp butter for extra richness)
  • 2 tablespoon -3 milk or cream (optional)
  • 2 green onions, finely chopped
  • salt and black pepper

For knish assembly

  • 1 package puff pastry dough (2 sheets), defrosted if frozen about 14-17 ounces pastry dough in total
  • 3 1/2 cups root vegetable mash (made with ingredients above) cold leftovers is fine
  • 1 egg plus one tablespoon water, mixed (for egg wash)

Instructions

  • HEAT OVEN to 375F/190C.
  • MAKE ROOT VEGETABLE FILLING:  (can be done 2-3 days ahead)
    °Prep and boil: Cut veggies into roughly the same size - about 1 - 1 1/2 inches (3-4 cm). If using carrots, slice them thinner as they take longer to cook. Place in a large pot and add water to cover by 1 inch/2.5 cm. Add 2 tsp salt. Bring to boil. Lower to medium heat and gently boil for 15-18 minutes or until soft and easily pierced with a fork. Drain vegetables in a colander and return to the pot.
    °Mash: On medium heat, shake cooked vegetables to dry them out for 1 minute. Add green onions, butter and milk/cream. Mash with a fork or potato masher to get the consistency you like. Do not use a food processor or immersion blender to mash veggies. Taste and add salt and pepper as needed. Set aside or store in fridge until ready to make knishes.
  • ASSEMBLE KNISHES: On a lightly floured cutting board, unroll one sheet of dough. It should be about 1/8-1/4 inch (3-6 mm) thick. Stretch it out a bit to make a large rectangle. Spread a log of vegetable mash mixture along the longer side of the rectangle - about 2 inches thick. Roll dough over the vegetable mixture about 1 and 1/2 times, making a log/roll. Cut away rest of dough for the next roll. Pinch seams together well (dip your fingertips in a little water if needed). Repeat with other half of dough on that sheet. Then do the same with the second sheet of dough. You will have 4 logs/rolls in total.
    one roll of filled puff pastry with second not yet rolled up
  • BAKE: Place filled knish rolls - 2 inches/5 cm apart - on a large baking sheet lined with parchment paper, seam side down. Brush egg wash on rolls to create a glazed golden look. Bake for 35-40 minutes until golden brown and flaky. Cut rolls into 2 inch/5 cm pieces on the diagonal and serve. Or see Note 4 for make ahead options.

Notes

  1. Root Vegetables options: Use two or more – white potatoes (I like Yukon/yellow potatoes best), sweet potatoes, carrots, parsnips, turnips, rutabaga (swede), celery root (celeriac). If you don't have a scale, don't worry. Leftovers are great. I use two white potatoes, 1 medium sweet potato, 2 medium carrots, 2 parsnips and 1 celeriac (or large turnip). 
  2. Variations and substitutes for root vegetable mash:
    • Lower calorie version: Reduce the butter and eliminate the cream or milk (or replace it with low fat Greek yogurt or broth)
    • Dairy free version: Substitute the butter with olive oil and the cream with broth.
    • Add ins: Try adding grated cheese, caramelized onions, caramelized leeks and/or chopped fresh chives.
    • Seasonings: Add a teaspoon of dried thyme or dill if you like. Or use a tablespoon of finely chopped fresh herbs.
  3. Other variations:
    • Try a different filling: Instead of root vegetable mash or mashed potatoes with fried onions, try creamed spinach, mushroom and onion, or ground beef and potatoes.
    • Make your own dough: If you want to get more traditional, here's a well-reviewed knish recipe with homemade dough from Food52.
  4. Make Ahead options:
    • Make the root vegetable mash 2-3 days ahead. Keep it in a large bowl covered tightly with plastic wrap or in an airtight container in the fridge. 
    • Freeze the unbaked knish rolls up to 2 months ahead in logs, unbaked, wrapped well in parchment and ziploc bags or foil. Bake as per instructions whenever you need them (no need to defrost).
    • Bake the knishes a couple of hours before you need them including cutting them into serving pieces. Keep them on the counter. Reheat them in the pan in a pre-heated 350F/177C oven for 6-8 minutes.  (I do this all the time - extra crispy/flaky - and highly recommend it.)
    • Leftovers: The best part of this recipe is that leftovers are great! For leftover knishes, store them in an airtight container in a single layer, in the fridge for up to a couple of days. Reheat them, tented with tin foil, at 350°F (177°C) for about 10-15 minutes or until they're heated through and crispy.
 
Nutrition values are rough estimates depending on on puff pastry dough used and how root vegetable mash is made eg amount of butter and milk/cream used.  
Calories: 106kcal | Carbohydrates: 11g | Protein: 1g | Fat: 6g | Saturated Fat: 2g | Cholesterol: 2mg | Sodium: 45mg | Potassium: 112mg | Fiber: 2g | Sugar: 1g | Vitamin A: 28IU | Vitamin C: 5mg | Calcium: 13mg | Iron: 1mg