Sea cucumbers are high in protein, with most species comprising 41–63% protein. https://www.healthline.com/nutrition/sea-cucumber#nutrition

Sea cucumber is a marine invertebrate found all over the world. It is used in traditional Chinese medicine to treat fatigue, impotence, constipation, frequent urination, and joint pain. It is also a rich source of mucopolysaccharides, especially chondroitin sulfate, commonly used for arthritis. https://www.mskcc.org/cancer-care/integrative-medicine/herbs/sea-cucumber

Slowly cook the soaked sea cucumber in boiling water for 20 to 30 minutes. Turn off the heat afterwards, cover and let cool. Cut it open and remove the organs inside. If the sea cucumber still feels hard, repeat the boiling process for two or three times, until it turns completely soft.

https://guide.michelin.com/en/article/features/ingredient-sea-cucumber

The medicinal value of sea cucumbers:

1. Sea cucumbers are rich in protein, less fat, and cholesterol. 
2. Sea cucumbers are known as "Arginine Monopoly". Contains 8 kinds of essential amino acids that cannot be synthesized by the human body, of which arginine and lysine are the most abundant. 
3. Ginseng is rich in trace elements, especially calcium, vanadium, sodium, selenium, and magnesium. The trace element vanadium contained in sea cucumbers ranks first among various foods, which can participate in the transport of iron in the blood and enhance hematopoietic capacity. 
4. Contains special active nutrients, sea cucumber acid mucopolysaccharide, sea cucumber saponin (sea cucumber, sea cucumber toxin), sea cucumber lipid, sea cucumber gel protein, taurine, etc.

Contraindications of sea cucumber:  Patients suffering from acute enteritis, bacillary dysentery, colds, sputum expectoration, asthma, and loose stools, bleeding with stasis, and dampness blockage should avoid use. 

Recipe 

Sea Cucumber Lean Broth 

Ingedients

Prepared 1 sea cucumber, 200 grams of lean meat, 2 red dates, and 2 slices of ginger; 

Rinse the sea cucumber with water and soak it for several hours and parboil to soften the body, clean the impurities from the belly, remove the internal tendons and slice the sea cucumber. 

Cut the lean meat into cubes, and clean the red dates. 

Put all the ingredients into the stewing pot and simmer for about one and a half hours. 

Sea cucumber is warm and salty in nature; it enters the Heart and Kidney meridians and can nourish the kidney, blood and moisturize dryness. This soup can help to nourish the kidney/adrenal energy and brain, also nourish the marrow and blood.