Carmelized Onion and Mustard Tart

So Tim was in a favorite independent bookstore when on the sale table he saw The Accidental Vegetarian for like $8. It's a fun story-of-a-cookbook about a gentleman in England who bought a vegan restaurant knowing nothing about running a restaurant, or vegetarian cooking! Well, his recipe for a mustard-onion tart jumped right out at us, and it is the first thing we have tried from this book.

After making the rich pastry dough, you slice 4 large onions... these were some powerful onions that had Tim avoiding the kitchen as their fumes were causing tears a room away.

It is always amazing to me how much onions reduce... especially after 40 minutes of cooking:

Some cream, eggs and the whole grain mustard are added to the onions and put into the blind-baked crust (which, but the way, was supposed to be in a tart pan... I don't have a tart pan, so I used my springform pan... gonna go buy a tart pan)

This all bakes and comes out slightly browned and looking kinda rustic.

It is thick, not custardy (which is a good thing in my book), and sweet due to the slow-cooked onions as well as the mustard and pastry. We served this with steak and our favorite syrah, and had its leftovers with a salad and surprisingly good grape tomatoes. We think this will be a good summer dinner with fresh-off-the-vine tomatoes.

The recipe: From The Accidental Vegetarian, by Simon Rimmer

Pastry:

1 3/4 cups flour
6 Tbsp unsalted butter, chilled and cubed
pinch of salt
3 1/2 tbsp(I needed more) milk
1 egg yolk

1. Put flour, butter and salt in a food processor and pulse until crumbly.
2. Add the milk and egg yolk and pulse until a dough forms
3. Turn out the dough onto a floured work surface and kneed slightly and form into a flat disk. Wrap in saran wrap and chill at least 1 hour (great to make ahead of time so it's ready whenever you are)

Carmelized Onion and Mustard Tart:

4 Tbsp unsalted butter
1 Tbsp vegetable oil
4 large spanish onions, sliced
1 clove of garlic (he says crushed, I minced)
2 whole eggs plus 2 egg yolks
2 Tbsp whoel grain mustard
2/3 cup heavy cream
salt and pepper

Preheat oven to 400F
1. Roll out the pastry to fit an 8-10" tart pan (as I said above, I used a springform pan... a pie pan should work as well). Press into pan and chill for 20 minutes.
2. Bake the pastry for 25-30 minutes until crisp and dry. (he does not say to weight it down, but this needs to be done or else it puffs up)
3. While the pastry bakes, melt butter and oil in a pan over low heat and add the onions, garlic and salt and pepper. Cook slowly until the onions are golden but not burned... about 40 minutes.
4. Whisk the eggs, egg yolks, mustard and cream together. Mix into the carmelized onions.
5. Reduce oven temperature to 350F. Add onion mixture to pastry shell, and baked for 20 minutes until set firm and golden.