Mushrooms have a meaty quality perfectly suited to mimicking a roast beef sandwich. Wrapped in a chewy baguette, smothered in peppery sinus-clearing horseradish cream and dipped in a rich mushroom garlic broth–heaven on a plate.
Mushroom Jus (makes about 2 cups, enough for 4 sandwiches)
This is the most time-consuming part of the recipe. The roasted mushrooms, horseradish cream, toasted baguette–minutes away. To allow you to throw this sandwich together whenever you like, make a large batch of the jus, freeze it in ice-cube trays and thaw out small portions as needed.
6 cups (1 liter plus 480ml) water
6 oz. (172g) cremini mushrooms, roughly chopped stems and all
1/2 oz. (15g) dried porcini mushrooms
You can add the stems of the mushrooms you’ll be roasting as well
3 cloves garlic, skins on, smashed with a knife
Small handful of fresh flat leaf parsley
1 Tbsp. (15ml) tamari or soy sauce
A few grinds fresh black pepper
Add everything to a pot, bring to a boil, reduce to a simmer and let cook for at least one hour, more if you want to enhance the flavor. The more you cook it, the more it reduces, the stronger the flavor. You just want to leave yourself (and friends) enough for dipping. It’s a good idea to strain the finished jus through a coffee filter or paper towel to remove the sediment often accompanying dried porcini mushrooms.
Set aside or freeze for later.
Horseradish Cream (per person)
You can also use prepared horseradish instead of the fresh root, but the fresh is pretty amazing stuff. You’re likely to find it in the vegetable aisle next to the fresh herbs and root vegetables.
2 Tbsp. (30ml) sour cream
1 Tbsp. (15ml) freshly finely grated horseradish root, about 1/8 ounce (3.75g)–use a microplane if you have one
1 Tbsp. (15ml) fresh flatleaf parsley, minced
Squeeze of fresh lemon juice
Roasted Mushrooms (per person)
I used shitake and portobello. The shitakes get crisp and chewy and the portobellos buttery and tender which makes for a nice contrast in texture. Button mushrooms, cremini, chanterelles, oyster, king trumpet are possible substitutes.
3 oz. (90g) of mushrooms, stems removed, sliced–not too thin
1 Tbsp. (15ml) unsalted butter
1 Tbsp. (15ml) olive oil
1 clove garlic, smashed with root end intact and skin removed
In a skillet over medium heat, melt the butter into the oil. Add the garlic and cook for about 3 minutes. Remove the garlic.
In a bowl, gently toss the sliced mushrooms with the butter/oil, a few pinches of salt and freshly ground black pepper.
Spread the mushrooms in a single layer on a foil-lined baking sheet.
Bake at 350F/175C degrees for about 15 minutes, turning the baking sheet 180 degrees halfway through to make sure they cook evenly.
To assemble the sandwiches:
Cut and split the baguette. I made 5-inch or 13cm sandwiches. Brush the inside of the bread with a little olive oil or butter and toast, fat side down until the bread is crispy and golden brown on the inside.
Spread each side with about 1 tablespoon (15ml) of horseradish cream. Pile the mushrooms on one half and top with the other. Using a serrated knife, cut the sandwich in two.