Cast Iron Tempeh Stir-Fry with Sweet Potato and Peanut Sauce (560 Cal, 42g Protein)

Tempeh is fermented soy — whole soybeans inoculated with Rhizopus oligosporus and bound into a dense, sliceable block. Fermentation matters here. It breaks down phytic acid, which means the iron, zinc, and magnesium in soy become far more bioavailable than in tofu or soy milk. A 2015 study confirmed that fermentation reduces phytate content in soybeans by up to 56%, directly increasing mineral absorption. At 200g per serving, tempeh delivers roughly 38g protein on its own — a complete amino acid profile with a PDCAAS of 0.99.

The peanut-ginger sauce is the binder. Peanut butter adds fat-soluble calories without excess volume, plus niacin — 2 tbsp covers roughly 25% of the daily value. Sweet potato cubes roast at 425°F until caramelized on the edges. One medium sweet potato provides over 400% of the daily value for vitamin A as beta-carotene, which is fat-soluble. The sesame oil and peanut butter in this dish provide the fat needed for absorption.

Ingredients

#

• 400g tempeh, sliced into 1/4-inch strips (200g per serving)
• 1 medium sweet potato (200g), peeled and cut into 1/2-inch cubes
• 2 cups bok choy, roughly chopped
• 1 medium carrot, sliced thin on the bias
• 2 tbsp tamari
• 1 tsp smoked paprika
• 2 tbsp natural peanut butter
• 1 tbsp rice vinegar
• 1 tsp sesame oil
• 1 tbsp lime juice
• 1 tsp fresh ginger, grated
• 1 clove garlic, minced
• 1 tbsp crushed peanuts
• 2 scallions, sliced thin
• 1 tsp avocado oil

400g tempeh, sliced into 1/4-inch strips
1 medium sweet potato (200g), peeled and cut into 1/2-inch cubes
2 cups bok choy, roughly chopped
1 medium carrot, sliced thin on the bias
2 tbsp tamari
1 tsp smoked paprika
2 tbsp natural peanut butter
1 tbsp rice vinegar
1 tsp sesame oil
1 tbsp lime juice
1 tsp fresh ginger, grated
1 clove garlic, minced
1 tbsp crushed peanuts
2 scallions, sliced thin
1 tsp avocado oil

Instructions

#

1. Preheat oven to 425°F. Toss the sweet potato cubes with a thin coat of avocado oil spray, spread on a parchment-lined sheet pan in a single layer, and roast for 20-25 minutes. Flip once at the 12-minute mark. You want caramelized edges and a soft center.
2. While the sweet potato roasts, slice the tempeh into 1/4-inch strips. Toss with 1 tbsp tamari and smoked paprika. Let it sit for at least 10 minutes — the tamari draws surface moisture out, which means better searing.
3. Make the peanut sauce. Combine peanut butter, remaining 1 tbsp tamari, rice vinegar, sesame oil, lime juice, grated ginger, and minced garlic in a small bowl. Whisk until smooth. Add 1-2 tbsp warm water to thin it to a pourable consistency.
4. Heat your cast iron skillet over medium-high heat. Add 1 tsp avocado oil. When the oil shimmers, lay the tempeh strips in a single layer. Do not move them for 3 minutes. Flip and sear another 2-3 minutes until both sides are deep brown and crispy at the edges. Remove and set aside.
5. In the same skillet, reduce heat to medium. Add the carrots and cook for 2 minutes. Add the bok choy and cook for 1-2 minutes until the greens wilt and the stems are barely tender. Do not overcook bok choy — it goes from crisp to limp in under a minute.
6. Return the tempeh and roasted sweet potato to the skillet. Pour the peanut sauce over everything and toss to coat. Cook for 30 seconds — long enough to warm the sauce through.
7. Plate and top with crushed peanuts and sliced scallions. The peanuts go on last to preserve the crunch.

CRON Notes

#

Tempeh fermentation and mineral bioavailability. Phytic acid in raw soybeans chelates iron, zinc, and calcium — binding them in the gut so you absorb a fraction of what the label says. Fermentation with Rhizopus oligosporus degrades phytate by 40-60%, releasing those minerals. This is why 200g tempeh delivers more absorbable iron than the same weight of tofu. The 5.2 mg iron per serving is non-heme, but the vitamin C from bok choy and lime enhances non-heme iron absorption by forming soluble iron-ascorbate complexes in the gut.

Sweet potato beta-carotene is the primary micronutrient driver in this recipe. One medium sweet potato contains roughly 1400 mcg RAE of vitamin A — over 400% of the daily value. Beta-carotene is fat-soluble, so the peanut butter and sesame oil in this dish are not optional additions. A study on dietary fat and beta-carotene demonstrated that co-ingestion of dietary fat increases beta-carotene absorption and bioconversion into vitamin A.

Bok choy calcium deserves more attention. Unlike most plant calcium sources, bok choy has low oxalate content, which means its calcium is highly bioavailable — roughly 50% absorption rate compared to 32% for milk. Two cups of bok choy contribute roughly 150 mg of absorbable calcium to this serving.