Remove and discard the leaves from <quantity>1<unit>bunch</unit></quantity> of thin Japanese knotweed. Finely chop the stems

Add <quantity>2<unit>tbsp</unit></quantity> of olive oil to a small saucepan and transfer the Japanese knotweed

Sweat over low heat until it turns dark green

Turn the heat to medium. Add <quantity>1<unit>cup</unit></quantity> of white vermouth and let it simmer for 1m to evaporate the alcohol

Add <quantity>1½<unit>cups</unit></quantity> of water and <quantity>½<unit>bunch</unit></quantity> of elderflower. Bring it to a boil and cook for 2m to extract the flavors

Blend on high speed until smooth

Strain through a fine mesh sieve and season with salt to taste. The Japanese knotweed sauce is ready

Enjoy using it to dress your favorite greens!