PREPARE THE ASPARAGUS
Set a medium heatproof bowl over a medium saucepan filled with 1-inch of gently simmering water. Add the egg yolks and whisk until foamy. Add the water and whisk until light and foamy and slightly thickened. Working in batches, whisk in the butter; adding more as each batch melts. Continue whisking until the sauce is thick. Remove from the heat, whisk in the lemon juice and season with salt, black pepper and cayenne.