Oyster and Egg Drop Soup | IDDSI Level 3 Liquidised Recipe

IDDSI Level 3 (Liquidised) | 35 minutes | Medium

Oysters are the richest dietary source of zinc among all commonly consumed foods, making them an exceptionally valuable ingredient for elderly residents — a population in whom zinc deficiency is prevalent and associated with impaired immunity, delayed wound healing and diminished taste sensitivity. This recipe cooks fresh oyster meat thoroughly in a clear broth, blends and strains the liquid to a completely smooth base, then incorporates beaten egg through a slow pour to form delicate egg threads, which are strained out again. The result is a fully liquidised, particle-free soup that flows freely through the tines of a fork, meets IDDSI Level 3 throughout, and delivers a concentrated, savoury flavour with minimal food volume.

Ingredients (2 servings)

Main:

• 150g fresh shucked oyster meat (canned pre-cooked oysters may be substituted)
• 2 eggs (beaten)
• 500ml low-sodium clear chicken broth
• 2 slices fresh ginger

Starch slurry:

• 1.5 tablespoons cornflour (corn starch)
• 3 tablespoons cold water

Seasoning:

• 1/4 teaspoon salt
• A pinch of white pepper
• A few drops sesame oil

Method

1. Wash the oyster meat gently in lightly salted water to remove any shell fragments and impurities. Rinse under cold water and pat dry with kitchen paper.
2. Bring the chicken broth to a boil with the ginger slices over high heat. Add the oyster meat and cook over medium heat for 4–5 minutes until fully cooked through — the edges of each oyster should be curled and the centre completely opaque.
3. Remove and discard the ginger slices. Transfer the oysters and broth to a blender. Blend on high speed for 60–90 seconds until completely liquefied.
4. Strain the blended liquid through a fine-mesh sieve back into the pot, pressing firmly with the back of a spoon to extract maximum liquid. Discard the residue remaining on the sieve.
5. Reheat the strained oyster liquid over low heat. Mix the cornflour with cold water until smooth. Pour slowly into the liquid while stirring continuously until a very light, flowing consistency is achieved — slightly more viscous than water, meeting Level 3.
6. Pour the beaten egg in a slow, fine stream into the gently simmering liquid while stirring slowly in a circular motion to form fine, delicate egg threads.
7. Once the egg threads have set (approximately 30 seconds), pass the soup through the fine-mesh sieve a second time — straining out all egg thread particles to achieve a completely smooth, particle-free Level 3 liquid.
8. Season with salt, white pepper and sesame oil. Serve at 60–70°C.

Texture Test

Fork flow test (Level 3): The soup flows freely through all gaps between the tines of a fork with no particles or residue left behind on the fork. Nothing is caught or retained by the fork.

Flow rate: Level 3 (Liquidised) sits between thin liquid (Level 1) and pureed (Level 4). The soup should flow easily around the bowl when tilted, with slightly more resistance than water — a mild, perceivable body. When tested with a syringe, it should empty within 10 seconds.

Why double-straining matters: Oyster fibre and egg thread particles are the two most common causes of texture non-compliance in this recipe. The second straining step is not optional — it is the safety step that achieves Level 3.

Safety Notes

⚠️ Oysters must be fully cooked — raw or undercooked oysters are a significant food safety risk (norovirus, Vibrio cholerae). For residents in care settings, cook oyster meat until the internal temperature reaches 75°C — the edges must be fully curled and the centre completely opaque throughout. Never use partially cooked oysters.

⚠️ Shellfish allergy — oysters are a regulated allergen. Confirm the resident’s allergy status before preparing this dish. For residents with shellfish allergy, this recipe is contraindicated.

⚠️ Both straining steps are mandatory — any residual oyster fibre or egg particle constitutes a texture safety failure at Level 3. Do not skip or abbreviate either straining step.

Sourcing in Hong Kong

• Fresh oyster meat: Wet market seafood stalls carry fresh shucked oyster meat, particularly during the autumn and winter months; PARKnSHOP and Wellcome stock canned cooked oysters as a year-round alternative (these are pre-cooked but should still be simmered for food safety)
• Low-sodium chicken broth: Available at all major supermarkets

Nutrition

Approximately 120 kcal per serving (about 200ml), 14g protein, 15mg zinc (approximately 136% of the adult daily recommended intake). Oysters provide the highest concentration of bioavailable zinc of any common food — a clinically meaningful quantity for elderly residents, in whom zinc deficiency is common and associated with impaired wound healing, reduced immune function and loss of appetite. Eggs contribute complete essential amino acids. Together, this soup delivers exceptional micronutrient density for its volume, making it particularly valuable for residents with small appetites and elevated nutritional needs.

Cultural Note

Oysters from the Pearl River Delta — particularly those from Shajing (沙井) in Shenzhen and Lau Fau Shan (流浮山) in the New Territories — have been a prized ingredient in Cantonese cooking for centuries, valued both for their flavour and their traditional reputation as a restorative food. Cantonese families have long cooked oyster congee and oyster soup to nourish the elderly and the recuperating. Presenting this IDDSI Level 3 version in care settings connects residents with that tradition of nourishment, while meeting the texture safety standards that protect those with severe dysphagia.