This open-face vegan sandwich of roasted sweet potato, onion, portobello, red pepper and rich, smoky walnut sauce is the simple meal you didn’t even know you needed in your life. It’s one of those “greater than the sum of its parts” kind of things. Don’t you love it when that happens?
The magic of these roasted vegetable sandwiches comes from the contrasting flavors and textures – think sweetness of onion and sweet potato, smokiness of smoked paprika, umami of portobellos, richness of walnuts, and the crispness of fresh lettuce and perfectly toasted bread. I mean, this sandwich ticks all the delicious boxes! I really don’t have much else to say except that you just HAVE to try it.
Dietary Options for these Roasted Vegetable Sandwiches
- You can easily make this recipe gluten-free by using your favorite gluten-free bread.
- To make it oil-free, simply roast the veggies with a bit of broth instead of oil, and use your favorite oil-free whole-grain bread.
Not in the mood for a sandwich? No problem! The veggies and sauce would be perfect…
- atop a bowl of brown rice or a big salad
- in a wrap
- on pizza or flatbread
Or in whatever delicious combination you can dream up! Trust me when I say you’ll want to put this walnut sauce on everything.
Here’s one more idea: turn this into crostini and serve it at your next party!
I truly love these flavors, and I hope you do, too!
You might also like Chickpea Salad With Dill (+ Oil-Free Mayo Recipe)!
Roasted Vegetable Sandwiches With Smoky Walnut Sauce
- 1 sweet potato, peeled, sliced lengthwise into 1/4-inch-thick "steaks"
- 1 onion, sliced
- 2 portobello caps, stems removed
- 1 red pepper, cut into thick strips
- 2 cloves garlic, peeled
- 1 Tbsp oil for roasting, optional (for oil-free, sub 2 Tbsp vegetable broth or a mixture of soy sauce and water; omit salt listed on the next line)
- 1 large handful mixed lettuce greens
- 2 to 4 slices sourdough or thick bread of choice
For the walnut sauce:
- 2/3 cup raw walnut halves
- 1/2 tsp salt
- 1/2 tsp smoked paprika
- 1 tsp balsamic vinegar
- 1 to 2 Tbsp water for thinning
Roast the vegetables:
- Preheat the oven to 450 degrees. Line a large baking sheet with parchment or a silicone mat.
- Lightly oil the vegetables (or coat in broth). Arrange the vegetables in a single layer on the baking sheet, with the mushrooms gill-side up. Sprinkle a pinch of salt on everything except the portobellos.
- Bake for 15 minutes. Remove from the oven, and transfer the two garlic cloves to the bowl of a food processor. Flip the sweet potato, onion and red pepper. Leave the portobellos gill-side up and sprinkle them with salt. Return the pan to the oven and bake until the vegetables show slight browning and the sweet potatoes are tender, an additional 10 to 15 minutes.
Make the walnut sauce:
- In a food processor combine the two cloves of garlic that were removed from the oven, walnuts, salt, and smoked paprika. Pulse until the nuts are very finely chopped. With the machine running, quickly drizzle in the water and balsamic, stopping to scrape down the sides as needed. Taste for seasoning, and add black pepper. The consistency should be a thick, slightly chunky, spreadable dip.
Assemble the sandwiches:
- Toast the bread. Slice the portobello caps. Spread a layer of walnut sauce on each piece of toast and top with the roasted vegetables. Lightly dress the lettuce with a spoonful or two of the walnut sauce and pile on top of each sandwich.