Like all Shakespeare plays, Henry V contains shifting moods and contrasting scenes. In a play that celebrates an amazing military victory, there are unsurprisingly rousing and patriotic speeches, the best known of which is the "Crispin's day" one delivered by Henry to motivate his dispirited troops immediately before the battle (Act IV, Scene 3). But there are also moments of sorrow and difficult decisions: Henry has to abide by the rules of military engagement and order the execution of his former drinking companion, Bardolph, for "robbing a church". And, of course, there are moments of humour, which is where the food comes in.
For symbolic purposes, Henry's winning army contains officers from all regions of the British Isles, including Fluellen from Wales. Fluellen cannot cease boasting of his Welsh heritage, and of that of Henry himself, who was born in Monmouth in 1386. When Henry admits his pride in being a Welshman and in wearing the leek, Fluellen expresses his delight in his Welsh accent:
All the water in Wye cannot wash your majesty's Welsh plood out of your pody, I can tell you
that: God pless it and preserve it, as long as it pleases his grace, and his majesty too.
(Act IV, Scene 7)
For more on this - and the leek tart it inspired - read here