Espárragos de Navarra

White asparagus is the emblematic vegetable of the lower Ebro, grown across Navarre and adjoining stretches of Aragón and La Rioja. It carried a Spanish 'specific designation' from 1986 and was registered as a European Protected Geographical Indication, 'Espárrago de Navarra', in 2003. The asparagus is white because it is earthed up and cut below the surface before light reaches the tip, which keeps it pale and stops bitterness developing; the cold nights of the Ebro plain are credited with its tender, low-fibre flesh.

A thick, ivory spear, peeled smooth, tender enough to cut with the side of a fork. The flavour is delicate, faintly sweet and grassy with almost no bitterness, and the texture is soft and watery rather than fibrous. Served cool. The mayonnaise adds richness, the vinaigrette a bright vinegar edge — the asparagus itself is mild enough to take either.

Two techniques define it. In the field, the spear is blanched in the agronomic sense — earthed up so it grows in darkness, which prevents chlorophyll forming and keeps the flesh white and mild. In the kitchen, the woody base is peeled and the spears are blanched in the culinary sense, simmered in salted water until just tender then cooled, which sets a clean colour and stops the cooking before the spear goes limp. The two table sauces are an emulsion contrast: mayonnaise is a stable oil-in-egg emulsion, the vinaigrette a loose, temporary oil-and-vinegar one.