Defrost peas at room temperature. Peel onions and cut into cubes. Knead minced meat, half onion cubes, egg, breadcrumbs, mustard and sambal oelek. Season with salt. Form minced meat into 12 rolls.
Heat the oil in a large frying pan. Fry the minced meat rolls over medium heat for about 8 minutes while turning. In the meantime melt butter. Sauté the remaining onion for about 6 minutes until translucent. Add peas after 3 minutes.
Pour in the stock and cook for another 5 minutes. Wash the mint, shake dry and, except for something to garnish, pluck leaves from the stalks and chop them. Pour the peas into a sieve, collecting the stock.
Add lime juice, mint and 5 tablespoons of vegetable stock to the peas. Puree with a blender. Season to taste with salt and pepper. Arrange puree and minced rolls on plates and garnish with mint.