This is a lentil-mushroom meatball sub with cashew mozzarella and marinara, loaded into a toasted roll. It takes about 25 minutes of prep before the meatballs go in the oven, and the result is a filling, saucy sandwich that holds together well. If you’ve been curious about plant-based cooking but not sure where to start, this is a good one — the ingredients are inexpensive and the steps are straightforward.
Ingredient notes
- Flaxseed meal: This is just ground flaxseeds — find it near the nuts or baking aisle. Mixed with water, it thickens into a gel that holds the meatballs together. Don’t skip it or swap whole flaxseeds; they won’t bind the same way.
- Tapioca starch: This is what makes the cashew mozzarella stretchy when heated. It’s sold near the gluten-free flours or in Asian grocery stores. Arrowroot starch works in a pinch but gives a slightly less elastic result.
- Raw cashews: They need to be raw, not roasted or salted, for the cheese to blend smooth. Soak them in cold water for at least 4 hours, or cover with boiling water and soak 30 minutes if you’re short on time.
- Cremini mushrooms: White button mushrooms are a fine substitute. The goal is moisture and umami, and both deliver it.
- Walnuts: These add a slightly meaty texture. If you need a nut-free version, raw sunflower seeds work well and won’t change the flavor much.
Why this recipe works
Two things matter most here. First, the meatball mixture is baked before it goes into the marinara — baking firms the outside so the balls don’t fall apart when they simmer in the sauce. If you skip the bake and go straight to simmering, you’ll end up with a chunky sauce instead of meatballs. Second, the sub roll gets brushed with olive oil and toasted. A soft, untoasted roll turns soggy fast under the marinara and cheese. Toasting takes two minutes and is the difference between a sandwich that holds up and one that collapses halfway through eating.
Common problems and fixes
- Meatballs crumble when you roll them: The mixture is probably too wet. Add a tablespoon of oats at a time and let the mixture sit for five minutes — the oats absorb moisture and the mix will firm up enough to shape.
- Cashew cheese stays liquid and won’t stretch: It needs steady heat and constant stirring. If it looks thin after a couple of minutes, keep going — it tightens up quickly once it reaches the right temperature. Make sure you’re using tapioca starch, not cornstarch.
- Meatballs stick to the baking sheet: Line the pan with parchment paper, not just a light spray. Lentil-based mixtures have enough natural starch to bond to bare metal.
- The sub is too wet to eat neatly: Use a slotted spoon to transfer the meatballs so excess marinara stays in the pan. Add sauce to the roll separately so you control how much goes in.
- Meatballs taste flat: Taste the raw mixture before shaping — lentils and oats absorb a lot of seasoning. Add salt and a pinch more dried oregano or fennel seed if it needs a lift before it goes in the oven.
Leftovers and meal prep
Baked meatballs keep in an airtight container in the fridge for up to 4 days, and they freeze well for up to 2 months — freeze them on a flat tray first so they don’t stick together, then transfer to a bag. Reheat from frozen in a 375°F oven for about 15 minutes, or simmer directly in marinara over low heat until warmed through. The cashew mozzarella keeps refrigerated for 3 days; reheat it gently in a small saucepan over low heat with a splash of plant milk to loosen it. Skip making the cheese ahead if you’re new to this — fresh is easier to judge for texture, and it only takes about 10 minutes to make.
Vegan Meatball Sub
Equipment
- Food processor
- Oven
- Baking sheet
- Non-stick skillet
- Small saucepan
- High-speed blender
Ingredients
For the Vegan Meatballs:
- 1 cup green or brown lentils cooked and drained
- 1 cup cremini mushrooms finely chopped
- ½ cup rolled oats gluten-free if needed
- ½ cup walnuts lightly toasted
- 2 cloves garlic minced
- 2 tablespoons tomato paste
- 1 tablespoon flaxseed meal mixed with 2.5 tbsp water
- 1 teaspoon dried oregano
- ½ teaspoon salt to taste
- ¼ teaspoon freshly ground black pepper
For the Cashew Mozzarella:
- ½ cup raw cashews soaked for 4 hours or overnight
- ¾ cup plant-based milk unsweetened, plain
- 1 tablespoon tapioca starch
- ½ teaspoon apple cider vinegar
- ½ teaspoon salt
For the Assembly:
- 2 cups marinara sauce homemade or store-bought
- 4 pieces sub rolls vegan, about 6 inches each
- 1 tablespoon olive oil
- ¼ cup fresh basil leaves chopped, for garnish
Instructions
- Make the Meatballs: Preheat oven to 375°F (190°C). In a food processor, pulse oats and walnuts into a coarse meal. Add mushrooms, lentils, garlic, tomato paste, flax mixture, oregano, salt, and pepper. Pulse to combine, keeping some texture. Form into 1-inch balls and place on a baking sheet. Bake for 20–22 minutes until firm and lightly browned, turning once at the halfway mark.
- Prepare Cashew Mozzarella: Drain soaked cashews. In a high-speed blender, blend cashews, plant milk, tapioca starch, vinegar, and salt until smooth. Pour into a small saucepan over medium heat, stirring continuously until it thickens to a stretchy consistency, about 5–7 minutes. Remove from heat and set aside.
- Warm the Marinara: In a saucepan, simmer marinara sauce over low heat. Add the baked meatballs and gently coat them in the sauce for 5–7 minutes to absorb flavor.
- Toast the Rolls: Preheat a skillet or oven to medium heat. Brush sub rolls lightly with olive oil and toast until golden and crisp, about 2–3 minutes per side.
- Assemble the Subs: Open toasted rolls, layer 3–4 meatballs per roll, spoon extra marinara on top, drizzle generously with cashew mozzarella, and garnish with fresh basil.
Notes
- For gluten-free subs, use gluten-free rolls and ensure oats are certified GF.
- Swap walnuts with sunflower seeds for a nut-free version.
- Prepare cashew mozzarella up to 3 days ahead and reheat gently over low heat.
- Don't skip the flax mixture — it ensures the meatballs bind beautifully.
Nutrition
Your questions, answered
Can I use canned lentils instead of cooking them from scratch?
Yes, canned lentils work fine here. Drain and rinse them well, then spread them on a clean towel and pat dry — excess moisture is the main reason meatballs fall apart, and canned lentils hold more water than cooked-from-dry ones.
Can I use store-bought vegan cheese instead of making the cashew mozzarella?
Yes, any store-bought vegan mozzarella that melts will work. Look for a block or shredded style labeled as meltable — not all vegan cheeses melt well, and some just dry out in the oven.
Do the meatballs have to be baked, or can I pan-fry them?
You can pan-fry them in a lightly oiled skillet over medium heat, turning every couple of minutes until browned on most sides. Baking is easier if you’re making a full batch because you don’t have to stand over the stove, but pan-frying gives a slightly crispier exterior.
How do I keep the meatballs from getting mushy when I add them to the marinara?
Make sure they’re fully baked and firm before adding them to the sauce, and only simmer for 5 minutes or so — just long enough to heat through and absorb some flavor. Longer than that and the texture starts to soften.
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