In a large, heavy-bottomed pot, melt butter (or heat olive oil.) Add onions and cook until golden brown. Add sugar, balsamic vinegar, salt, and pepper. Continue cooking on medium heat, until onions soften and mixture thickens, about 20 minutes. Set aside and allow to cool while you prep the tart.
Pre-heat oven to 375-degrees. Lightly flour your work surface. Roll out an 8-ounce puff pastry sheet to about 16”. Transfer to a lightly greased baking sheet. Fold over edges of pastry sheet about 1”. Pierce sheet with a fork (which will prevent the tart from puffing up.)
In a small bowl, mix together egg and gruyere. Spread evenly across puff pastry. Then, spoon caramelized onion on top, reserving any excess onion. Finally, line asparagus spears vertically across. Brush with asparagus and pastry crust with olive oil, sprinkle with salt and pepper, and bake for 20-30 minutes, or until crust is golden brown.
Remove from oven and allow to cool for about 10 minutes. Cut tart into square pieces and serve with freshly grated gruyere or parmesan. It’s delightful when served warm, but also great cold or at room temperature.
- Seek out peaches that are heavy for their size, as that’s usually a good indicator that the fruit will be juicy.
- Press peaches gently at the top near where the stem was—if the flesh yields slightly, the fruit is ripe and ready to eat. Harder peaches can be ripened at home, but you’ll want to skip any that are rock hard, as those were picked too soon. Really soft peaches are over-ripe but they’re still good for baking. Avoid peaches with bruises, scratches or soft spot.
- Seek out peaches that are heavy for their size, as that’s usually a good indicator that the fruit will be juicy.
- Press peaches gently at the top near where the stem was—if the flesh yields slightly, the fruit is ripe and ready to eat. Harder peaches can be ripened at home, but you’ll want to skip any that are rock hard, as those were picked too soon. Really soft peaches are over-ripe but they're still good for baking. Avoid peaches with bruises, scratches or soft spot.
- To speed up the ripening process, place the fruit in a paper bag and leave it on the countertop. If peaches ripen too quickly, store them in the refrigerator for a few days, but keep a close eye—wrinkled skin means the fruit is starting to dry out.
Ingredients
Directions
In a large, heavy-bottomed pot, melt butter (or heat olive oil.) Add onions and cook until golden brown. Add sugar, balsamic vinegar, salt, and pepper. Continue cooking on medium heat, until onions soften and mixture thickens, about 20 minutes. Set aside and allow to cool while you prep the tart.
Pre-heat oven to 375-degrees. Lightly flour your work surface. Roll out an 8-ounce puff pastry sheet to about 16”. Transfer to a lightly greased baking sheet. Fold over edges of pastry sheet about 1”. Pierce sheet with a fork (which will prevent the tart from puffing up.)
In a small bowl, mix together egg and gruyere. Spread evenly across puff pastry. Then, spoon caramelized onion on top, reserving any excess onion. Finally, line asparagus spears vertically across. Brush with asparagus and pastry crust with olive oil, sprinkle with salt and pepper, and bake for 20-30 minutes, or until crust is golden brown.
Remove from oven and allow to cool for about 10 minutes. Cut tart into square pieces and serve with freshly grated gruyere or parmesan. It’s delightful when served warm, but also great cold or at room temperature.