Prepare the spaetzle in boiling salted water according to the instructions on the packet. For the Gremolata, wash the parsley, shake dry, pluck the leaves from the stalks and chop, except for something to garnish.
Wash the lemon hot, grate dry and peel the rind in short strips with a zest ripper. Halve the lemon and squeeze the juice from one half. Cut the remaining half into slices to garnish.
Wash the chilli and cut into thin rings. Mix parsley, chili, lemon peel, 1 tablespoon lemon juice and oil and season with salt. Drain the spaetzle and let it drain. Heat the fat in a pan and fry the spaetzle for about 10 minutes while turning.
Peel and roughly dice the onion. Wash apple, cut into quarters, remove core. Cut quarter into slices. Add onion and apple to the spaetzle and fry the last 5 minutes.
Season to taste with salt and pepper. Cut the maties into pieces. Spread the matie and gremolata over the finished spaetzle pan. Garnish with parsley and lemon.