Oca (Oxalis tuberosa) - The Colorful Gold of the Incas

Colorful, ribbed tubers that glow like little gems? The sight of this fascinating vegetable is guaranteed to turn heads! Oca is not only a true rarity in our gardens, but also the most important root vegetable of the Andes after the potato. If you're looking for a new, refreshing taste experience, this tuberous vegetable is for you: the spectacularly colored tubers in red, pink, yellow, white and orange tones combine a crisp texture with a delicate, lemon-fresh aroma that becomes wonderfully sweet and nutty when cooked – exactly as the Incas appreciated it millennia ago.

Scope of delivery: One young plant in a 7cm pot.

Growth & Appearance

• Lifespan: Perennial, but usually cultivated as an annual here, as the tubers are harvested in late autumn.

• Growth height: Grows as a bushy, compact plant and reaches about 30 to 50 cm in height.

• Habit: Ground-covering and cushion-like with fleshy, red-tinged stems and juicy green, clover-like leaves. It also makes a wonderful decorative underplanting.

• Flower & Fruit: Small, bright yellow funnel-shaped flowers appear in summer. But the real highlight grows hidden underground: the colorful, shiny tubers with their distinctive, furrowed structure.

• Ingredients: Oca belongs to the wood sorrel family and, just like rhubarb or sorrel, contains oxalic acid, which gives it its refreshing acidity when raw. Those sensitive to oxalic acid should preferably enjoy it cooked.

Interesting facts

• Other names: In addition to the common name Oca or Oka, the plant is known in German as Knolliger Sauerklee (tuberous wood sorrel) or Peruanischer Sauerklee (Peruvian wood sorrel). In the indigenous Quechua language, it is called Uqa. In New Zealand, it is marketed as New Zealand Yam or simply Yam, while in Colombia and Venezuela it is found under the names Hibia or Cuiba.

• Origin & History: Its home is the harsh highland regions of the Andes (especially Peru and Bolivia), where it was intensively cultivated already in pre-Columbian times – long before the arrival of Europeans. For the indigenous peoples and later the Incas, Oca was an essential staple food that significantly contributed to food security. It is an extreme adaptive artist that grows at altitudes of up to 4,000 meters and easily copes with cool, rainy summers and barren, stony soils. In the mid-19th century, the plant came to Europe and a little later to New Zealand. While it remained an absolute rarity in Europe for a long time, it is now extremely popular in New Zealand and can be found in every supermarket.

• Curiosities from its home country: In South America, there is a traditional method: after harvesting, the Oca tubers are placed in direct sunlight for a few days. This process is called "curing". This breaks down the oxalic acid and the tubers become significantly sweeter.

Use

• In the kitchen: An absolute all-rounder! Raw and sliced, the tubers add a crisp texture and a lemony kick to any salad. Cooked, fried, or as roasted vegetables, they develop their soft, sweet, potato-like aroma. Tip: The sour leaves can also be used as a decorative salad garnish.

Location, Care & other important things

• Location: Sunny to partial shade. Oca prefers it rather cool and moist in summer – it tolerates hot, extremely dry locations less well.

• Care: Cultivation is very straightforward. It needs loose soil and regular watering. The most important thing is patience: Oca is a short-day plant. Tuber formation only begins late in the year (from September), when the days become significantly shorter. The stems can be mounded in autumn like potatoes to increase the yield.

• Harvest & Wintering: Harvest as late as possible. Only when the first severe frost kills the above-ground leaves is it time to dig up the tubers. If you want to grow Oca again next year, store some of the tubers in a dark, cool, and frost-free place (e.g., in moist sand). In spring, these can then be planted again as seeds.

Planting out & Location

• Outdoors: Only after the Ice Saints (mid-May), when there is no longer a threat of late ground frosts.

• Tip for cultivation: Since Oca needs as long a frost-free autumn as possible for a rich tuber formation, it is recommended to plant it directly in large pots (at least 10 to 15 liters) or raised beds. When the first frosts threaten at the end of October, the pot can be moved to a protected house wall or into the greenhouse. This extends the growth phase by valuable weeks.

Traditional Recipe: Baked Oca Andean Style (Oca al Horno)

In the Andes, Oca is often prepared very simply to highlight its natural flavor. This traditional recipe uses the "curing" process in the sun to make the tubers particularly sweet.

Ingredients:

• 500 g Oca tubers (unpeeled)

• 1 to 2 tablespoons vegetable oil

• Coarse sea salt

• Pairs well with: A mild, fresh cheese (e.g., Queso Fresco, alternatively shepherd's cheese or cottage cheese) and a slightly spicy chili salsa.

Preparation:

1. The "Curing": Place the freshly harvested tubers in a sunny spot (e.g., on the windowsill) for 3 to 5 days.

2. Thoroughly brush the sun-ripened tubers under running water. Leave the skin on, as it gets a great texture when baked.

3. Toss the tubers with the oil in a bowl until lightly coated.

4. Spread them on a baking sheet and bake in a preheated oven at 200°C (top/bottom heat) for about 20 to 30 minutes. The Oca are ready when they give slightly to pressure and the skin begins to wrinkle slightly.

5. Sprinkle the warm tubers with coarse sea salt and traditionally serve with fresh cheese.