Combine garlic, onion, tiger prawn heads and shells, and water in a blender. Blend until a smooth pulp forms.

Transfer the pulp into a filter bag. Place the kombu inside the same filter bag.

Seal the filter bag under vacuum and cook sous vide at 186°F (85.5°C) for 1 hour.

After cooking, Cool the extracted liquid immediately in an ice bath.

Once cooled remove the filter bag and strain thoroughly, pressing and compressing the bag to extract as much liquid as possible.

Once cooled, add the salt and 34 g of pre-hy clarified xanthan gum water. Blend again until fully emulsified and incorporated.

Combine Roma tomatoes, shio koji, fresh lemon zest, preserved lemon skin, long pepper, and saffron in a high-speed blender. Blend on medium-high until smooth.

Transfer the mixture to a Thermomix or a similar temperature-controlled mixer and cook at 85°C (185°F) for 20 minutes.

Strain the cooked mixture through a filter bag and a fine sieve. Compress and squeeze the filter bag to extract all broth.

Combine equal parts of the tiger prawn extraction and the tomato broth to form the finished sauce.