Poached Shrimp with Sorrel-cilantro Sauce

In a blender, add the sorrel, cilantro, and water. Blend until the mixture is almost like juice. Strain through a fine sieve and set aside,  and discard what remains in the sieve. In a separate bowl, make mayonnaise by whisking together egg yolk, Dijon mustard, and a pinch of salt until combined. Whisking constantly, slowly drizzle in the oil a few drops at a time. When the mixture starts to look white and creamy, add the oil in a slow, steady stream. Whisk until fully combined. Add one-fourth cup of the sorrel-cilantro juice to the mayonnaise and whisk until smooth. Season with salt and pepper. Chill. Heat a large pot of water to boil. Add salt. Once boiling, add shrimp and cook until just barely pink, two to three minutes, depending on size. Remove shrimp and plunge into ice water to stop cooking. Once cold, strain and peel. Cut some in pieces, some in half, and leave some whole to create various textures. Place in a bowl and chill. When ready to serve, finely dice the fennel and radishes and add to the shrimp. Add the mayonnaise and toss to combine. Adjust seasoning and sorrel-cilantro juice to taste.