Step 1

Make the pickles: In a small saucepan over high heat, bring 1/2 cup of the water to a boil (or heat it in the microwave on HIGH for about 2 minutes), then add the sugar and salt, and stir to dissolve. Remove from the heat and add the remaining 1/2 cup water and the vinegar. Toss the carrot and daikon in the brine and let sit for at least 20 minutes and use right away, or transfer to an airtight container and refrigerate until needed.

Step 2

Make the pâté: If using the dried shiitakes, in a coffee/spice grinder, process the mushrooms until they form a powder, 30 seconds to 1 minute. If any large pieces of mushrooms remain after 1 minute, discard them. You should get about 2 tablespoons of powder.

Step 3

In a large skillet over medium-high heat, heat the sesame oil until it shimmers. Add the cremini mushrooms and shallot and saute, stirring regularly, until the mushrooms soften and brown, give up their liquid and it evaporates, about 10 minutes. Transfer the cremini mushrooms to the bowl of a food processor, add the shiitake powder, if using, and fermented beans and process until the mushrooms break down into a smooth paste. With the motor running, add the butter, 1 tablespoon at a time, letting it incorporate before adding more. Use right away, or refrigerate in an airtight container until needed. You should get about 1 1/4 cups.

Step 4

Make the sandwich: In the same skillet you used for cremini mushrooms, over medium-high heat, heat the oil until shimmering. Add the mushroom pieces, season with the salt and pepper, and cook until they release their liquid, it evaporates and they begin to brown on the bottom, about 8 minutes. (If you have something heavy, such as a small cast-iron skillet, use it to press the mushrooms to get a better sear.) Stir and brown the other side, an additional 5 minutes.

Step 5

Cut the baguette across the equator, leaving one of the long sides intact and open the bread like a sub roll (alternately, use the smaller sub rolls). Spread the pâté, warm or chilled, along the bottom half of the bread, then follow with the sauteed mushrooms. Top with the cucumber slices, quick pickles, cilantro leaves and jalapeño slices. Cut the baguette across into 4 pieces and serve. (Or assemble 4 individual subs on smaller rolls, dividing the ingredients evenly, and serve.)