Japanese Zucchini Onion Stir Fry

Last Tuesday, I came home to an almost-empty fridge and just happened to have two zucchini rolling around in the crisper drawer. My neighbor had mentioned this simple preparation she'd learned from her grandmother, and something about the combination of sesame and mirin sounded perfect for a night when I didn't want to think too hard about dinner.

I made this for my sister last week when she was recovering from a cold and needed something gentle but comforting. She kept stealing pieces straight from the pan before I could even get everything plated, which is always the best kind of review.

Ingredients

• 2 medium zucchini: Slice them into half-moons about 1/4 inch thick so they cook evenly and still have some bite
• 1 large yellow onion: Thinly slicing the onion creates delicate ribbons that caramelize sweetly alongside the zucchini
• 2 green onions: These add a fresh pop and mild onion flavor that brightens the whole dish
• 2 cloves garlic: Mince these finely so they disperse their aromatic magic throughout the stir fry
• 1-inch piece fresh ginger: Peel and mince this small the fresh zing makes such a difference compared to dried
• 2 tbsp soy sauce: This provides the salty foundation and that beautiful rich color
• 1 tbsp mirin: The subtle sweetness balances the soy and creates that restaurant-quality glaze
• 1 tsp toasted sesame oil: Use the toasted variety, not regular, for that deep nutty fragrance
• 1 tsp sugar: Just enough to help the sauce cling to the vegetables and round out the flavors
• 1 tbsp neutral oil: Canola or vegetable oil lets the other flavors shine without competing
• 1 tbsp toasted sesame seeds: Sprinkle these on top for a tiny crunch and visual appeal

Instructions

Mix the sauce ahead:

Whisk together the soy sauce, mirin, sesame oil, and sugar in a small bowl until the sugar completely dissolves

Get the pan hot:

Heat your neutral oil in a large skillet or wok over medium-high heat until it shimmers slightly

Start with the onions:

Add the sliced onions first and stir fry for about 2 minutes until they start to soften and turn translucent

Add the aromatics:

Toss in the garlic and ginger, stirring constantly for just 30 seconds until the fragrance fills your kitchen

Cook the zucchini:

Add the zucchini slices and stir fry for 3 to 4 minutes, moving them around constantly so they stay tender-crisp

Add the sauce:

Pour in your prepared sauce and toss everything together until the vegetables are evenly coated and glossy

Finish and serve:

Remove from heat immediately, sprinkle with green onions and sesame seeds, and serve while still hot

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This has become my go-to when I need a vegetable side that feels special but takes almost no effort. The way the sauce reduces just enough to coat everything is somehow satisfying every single time.

Making It Your Own

I've discovered that adding sliced mushrooms or bell peppers works beautifully if you want to bulk up the vegetables. Sometimes I throw in a handful of snap peas from the farmers market, and they add this wonderful sweetness.

What To Serve With It

This stir fry is incredibly versatile alongside simple grilled fish or a bowl of fluffy white rice. I've also served it over quinoa when I want something more substantial, and the nutty flavor of the grain complements the sesame perfectly.

Storage And Reheating

Leftovers keep surprisingly well in the refrigerator for up to two days, though the zucchini will soften a bit. Reheat gently in a skillet over medium heat rather than the microwave to preserve some texture.

• A splash of water helps revive the sauce when reheating
• Add fresh green onions after reheating to maintain their crunch
• Serve leftover stir fry over a fried egg for breakfast

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Sometimes the simplest recipes are the ones that end up in your regular rotation, and this Japanese-style stir fry has certainly earned its place in mine.

Recipe FAQs

→ Can I make this gluten-free?

Simply substitute regular soy sauce with gluten-free tamari. All other ingredients, including mirin, are naturally gluten-free. Double-check your tamari label to ensure it's certified gluten-free if you have severe sensitivity.

→ What vegetables work well as substitutions?

Bell peppers, snap peas, sliced mushrooms, or broccoli florets all work beautifully. Aim for vegetables that cook quickly and stay crisp. Add harder vegetables like carrots earlier in the cooking process so they become tender.

→ Can I prepare this ahead?

Pre-slice vegetables and mix the sauce up to a day in advance. Store separately in airtight containers in the refrigerator. The dish cooks quickly, so final preparation takes just minutes. However, it's best enjoyed immediately while vegetables retain their crisp texture.

→ What can I use instead of mirin?

Mix 1 tablespoon rice vinegar with 1/2 teaspoon sugar as a substitute. Dry sherry or white wine with a pinch of sugar also works in a pinch. The flavor profile will shift slightly but remains delicious.

→ How do I prevent zucchini from becoming mushy?

Cook over medium-high heat and keep vegetables moving in the pan. Don't overcrowd the wok or skillet—cook in batches if necessary. Remove from heat once zucchini is just tender, about 3–4 minutes. The residual heat will continue cooking slightly.

→ Is this suitable for meal prep?

Yes, though texture changes slightly upon reheating. Store in an airtight container for up to 3 days. Reheat gently in a skillet or microwave with a splash of water to refresh. The flavors often deepen overnight, making it tasty for next-day lunches.