Don’t you hate it when things don’t go according to plan? I went to bed on Sunday with my work clothes all picked out and a slow cooker of onions caramelizing away, but after I woke up with an unbelievable headache and then suffered a coughing fit that left me dizzy, I decided to call in sick. After downing some ibuprofen and an Emergency-C and forcing myself to sleep for a few more hours, I checked on the onions I had been caramelizing in the slow cooker over night.
Burnt. To. A. Crisp.
As much as I hate it when my plans get ruined, I double-hate it in the kitchen. I hate wasting food because it means wasting money, and I hate wondering over what went wrong – especially, as here, where it’s a technique that has worked for me before. I’d had my little heart set on making this roasted mushroom sandwich with onion gravy for several days. Thus, I forged ahead.
The extra step of recaramelizing the onions was well worth it, because this sandwich was pretty darn good. The roasted portobellos in combination with the rich caramelized onion gravy was meaty and comforting. Though I used chicken stock (because it’s what I had on hand), you could easily substitute some dark vegetable stock and make this a vegetarian sandwich that any meat eater would be happy to scarf down. The depth of flavor is really quite impressive, largely due to the extra step of caramelizing the onions. Roasting the mushrooms also brings out their natural meatiness, leaving them juicy with enough of a chewy texture to remain satisfying.
Roasted Mushroom Sandwich with Caramelized Onion Gravy
Caramelized Onion Gravy:
2 small onions, peeled, halved sliced lengthwise as uniform as possibly
2 tbs. olive oil, plus more if necessary
2 tbs. unsalted butter
1 tsp. kosher salt
1 tsp. freshly cracked black pepper
2 tsp. balsamic vinegar
1 1/2 tbs. all purpose flour
2 cups homemade chicken stock (or beef stock, or dark vegetable stock)
1 tbs. Worcestershire sauce
In a large sauté pan with high sides, add butter and olive oil over medium heat. Once butter is melted and frothing, add the onions and stir to form a uniform layer. Season with salt and pepper.
Continue to cook over medium heat, stirring every 1 minute to 2 minutes, until the onions are a deep mahogany color and are caramelized. This will take about half an hour to forty minutes. If necessary, add more olive oil or butter in order to keep the pan from drying out. You do not want to stir constantly, as this will prevent the onions from browning; nor do you want to stir too infrequently, as this will allow the onions to burn and become bitter.
If the onions have dried out when caramelized, add another tablespoon or two of olive oil along with the butter. Stir to evenly coat the onions and add balsamic. When butter is melted, sprinkle flour over the onions and necessary and whisk to combine. Constantly whisking, slowly add the chicken stock. Stir until smooth and reduce to desired consistency. Add Worcestershire and taste for seasonings, adjusting as necessary. If necessary, add another splash or two of chicken stock to maintain desired consistency.
[Note: This makes more gravy that required for the sandwiches. It would be excellent served with sausages, mashed potatoes or potato hash, over a meatloaf or with a slice of liver, or anywhere else you want some rich, flavorful gravy.]
1 6 oz. container sliced portobello mushrooms
3 tbs. olive oil
1/4 tsp. powdered garlic
Kosher salt and freshly cracked black pepper
Preheat oven to 400º.
On a tinfoil lined baking sheet toss mushrooms with olive oil, powdered garlic, salt, and pepper. Place in oven and roast 12-15 minutes, tossing once or twice, until the edges of the mushrooms are golden brown.
Roasted Mushroom Sandwich with Caramelized Onion Gravy:
Caramelized onion gravy (see above)
Roasted mushrooms (see above)
2 hamburger buns
2 slices provolone cheese
Place hamburger buns sandwich side down in the caramelized onion gravy and allow to soak for 1-2 minutes. You don’t want the buns to be mushy (unless you want to make this a fork and knife sandwich, which is totally acceptable), but you do want them to absorb some flavor. On the bottom bun, use some tongs to place a few onions on the bun. Add the mushrooms and top with a slice of provolone cheese.
Place under the broiler for one minute until cheese is melted and golden brown in spots. Top sandwich with other half of the bun and serve immediately.