Pasta with Portobello Mushrooms in Mustard Sauce

Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente, then drain and set aside.

Toast the pine nuts in a dry skillet over medium heat, stirring frequently, until golden and fragrant, about 3-4 minutes. Transfer to a plate and set aside.

Heat 1 tablespoon of olive oil in the same skillet over medium-high heat. Add the sliced portobello mushrooms and ½ tsp salt, then cook, stirring occasionally, until the mushrooms release their moisture and begin to brown, about 5-6 minutes. Transfer to a plate.

Add the remaining 1½ tablespoons of olive oil to the skillet over medium heat. Add the red onion slices and cook, stirring often, until softened and lightly caramelized, about 4-5 minutes.

Stir in the finely chopped garlic, minced rosemary, and red pepper flakes, and cook for 1 minute until fragrant.

Pour in the vegetable broth and mirin (or white wine), and bring to a simmer. Cook for 2 minutes to reduce slightly.

Whisk in the Dijon mustard until fully combined and smooth. Return the cooked mushrooms to the skillet and stir to coat evenly in the sauce.

Add the cooked pasta to the skillet and toss gently to combine, coating all the pasta with the mustard sauce. Season with remaining ½ tsp salt and adjust seasoning as needed.

Divide the pasta among serving bowls and top each portion with a generous sprinkle of the toasted pine nuts before serving.