Peel and finely chop the onion. Peel, wash and finely dice the potato. Heat oil in a pot, fry onion and potato until transparent. Add peas, except some for garnishing. Deglaze with broth, bring to the boil, cover and let it simmer for about 10 minutes
Wash the lemon and grate dry. Finely grate 1/4 of the peel, remove the rest in zests. Wash the mint, shake dry, pluck leaves from the stalks and add to the soup, except for a few leaves for garnishing
Mash the peas in the vegetable stock. Stir in 2 tablespoons of buttermilk. Season to taste with grated lemon peel, salt and pepper. Roast almonds in a pan without fat, remove. Cut ham into strips. Pour soup into a bowl. Garnish with ham, peas, 1 tablespoon buttermilk, mint, almonds and lemon zests