Natural form

A whole oncom cake showing its characteristic orange-mold-covered surface and firm pressed texture.

Shows the reader the intact cake form, distinctive mold color, and compressed block shape that define uncut oncom.

Proteins

Oncom

Indonesian fermented press-cake of peanut or soy, similar to tempeh, sliced and fried.

Oncom is a fermented food from West Java, Indonesia, made by inoculating peanut press-cake or soybean residue with mold until it knits into a firm cake. It is sliced and fried, crumbled into sambals, or wrapped in banana leaf. It has a savory, slightly nutty and earthy flavor and is a traditional protein source.

Oncom is a fermented cake of Indonesian origin, primarily produced in West Java's Sundanese cuisine, made from either peanut press-cake (bungkil kacang) — the residue left after peanut oil extraction — or soy pulp (ampas tahu), the wet remainder of tofu production. Unlike tempeh, which uses exclusively soybeans bound by Rhizopus mold, oncom embraces both waste streams of other food industries, making it an economical and ecologically sound product. The fermentation employs Neurospora intermedia (giving oncom kacang its signature red-orange speckled surface) or Rhizopus oligosporus, producing a cake that is denser, more intensely flavored, and slightly bitter compared to tempeh. The texture holds together firmly when sliced and resists crumbling in high-heat cooking. Historically sidelined outside Java by tempeh's international fame, oncom deserves recognition as a sophisticated fermentation in its own right — the Neurospora-produced variety develops a distinctive nutty, earthy, mildly funky character that deepens considerably with longer fermentation, and the process increases digestibility and B-vitamin availability just as with other mold-fermented legumes.

Measured in: g
Storage: Fridge

Allergens

PeanutSoy

Types & varieties

Oncom kacang (oncom merah)

Made from peanut press-cake; the characteristic red-orange speckled surface comes from Neurospora mold growth; the most common and widely available variety.

Oncom hitam

Black oncom produced from soy pulp; darker coloring develops with fermentation; carries a slightly stronger, more assertive flavor than the yellow variety.

Oncom kedelai

Yellowish oncom made from soy pulp; milder and less intense than the black variety; a good introduction for those new to oncom.

The Neurospora Difference

The presence of Neurospora intermedia sets oncom kacang apart from tempeh in both appearance and flavor. This orange bread-mold (Neurospora crassa, a close relative, is the famous genetic model organism) produces visible reddish spores on the cake's surface during fermentation. The mold contributes a subtle sweetness and intensifies the nuttiness of the peanut base while creating the characteristic color that signals proper fermentation. When you see an evenly orange-speckled surface, you know the fermentation progressed correctly.

Neurospora produces visible orange spores; Rhizopus-based fermentation appears white to gray
The orange color deepens as fermentation continues — check for even coverage before buying
Smell the cut surface: a pleasant mushroomy, earthy aroma indicates good fermentation; ammonia or sourness means it has gone bad

Common uses

Fried slices as gorengan — the classic street-food preparation, served hot with sambal for dippingGrilled whole or sliced, brushed with kecap manis until caramelized and lightly charredChopped and added to vegetable dishes and stir-fries in the final minutes of cookingSimmered in soups and stews characteristic of West Javanese cookingGround into sambal oncom — a pungent condiment of fermented cake pounded with fresh chilies and aromaticsCooked in coconut milk-based dishes; the dense texture holds together well in saucy preparationsPressed thin and pan-fried until crisp, then crumbled over rice as a protein-rich garnishStuffed into banana-leaf parcels with spices for a traditional Sundanese preparation

Tips & pitfalls

Select firm, evenly colored cakes without any gray, green, or slimy patches — these indicate spoilage or improper fermentation
Always cook oncom thoroughly before serving; while fermentation reduces some anti-nutrients, raw consumption carries risk of foodborne illness
For frying: slice 1–1.5 cm thick, pat completely dry with paper towels, and fry at 160–170°C until deep golden and crispy on both sides
To reduce bitterness present in some batches: soak slices in lightly salted water (about 1 tsp per cup) for 10–15 minutes before cooking
Freeze fresh oncom in portioned freezer bags; thaw slowly in the refrigerator overnight, never on the counter at room temperature
For grilling: slice thin (5–8 mm), score the surface in a crosshatch pattern to increase caramelization surface area, and brush with kecap manis halfway through cooking
The red-orange color on oncom kacang intensifies the longer fermentation continues — use your nose as well as your eyes; it should smell pleasantly aromatic, never rank or sour
Oncom is primarily a cottage-industry product — if sourcing from traditional markets, buy from vendors with high turnover to ensure freshness

Nutrition

339kcal

Energy

1418 kJ · per 100 g

Where the calories come from

Protein 8%Carbs 52%Fat 40%

Protein

14% DV

Carbs

44.3g

16% DV

Fat

15.2g

19% DV

Fiber

4% DV

Sodium

339mg

15% DV

Notable micronutrients

Selenium24% DV

Vitamin B1214% DV

Vitamin A10% DV

Riboflavin (B2)10% DV

Folate10% DV

Thiamin (B1)9% DV

Source · USDA FoodData Central · approx. Cake, coffeecake, cheese

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In the shops

Matched grocery products

No matched grocery products for Oncom yet.

Good to know

Origin: West Java, Indonesia (Sundanese cuisine)
Primary Materials: Peanut press-cake (bungkil kacang) or soy pulp (ampas tahu)
Fermentation Agent: Rhizopus oligosporus or Neurospora intermedia mold
Signature Color: Peanut oncom: reddish-orange from Neurospora; Soy oncom: pale yellow to black
Flavor Profile: Earthy, nutty, mildly funky; more intense than tempeh with subtle bitterness
Texture: Dense, firm cake that slices cleanly; holds shape when fried or grilled
Shelf Life: Refrigerate 3–5 days; freeze up to 1 month
Nutritional Value: Good plant protein source; fermentation improves digestibility and B-vitamin content

Substitutes

Tempeh — The most direct substitute; has a firmer texture and milder flavor. Soak briefly in warm water or broth if too firm, then proceed with identical frying or grilling techniques.
Fermented okara — Soy pulp (okara) fermented at home following a similar process produces a less dense but acceptable substitute when oncom is unavailable.

Pairs with

Kecap manisSambalCoconut milkGarlic and shallotsKencur (lesser galangal)

Also called

Fermented Press Cake