Peel and finely chop the onion. Clean, wash and cut the spring onions in thirds and lengthwise into strips. Wash tomatoes, dab dry and cut in half. Prepare noodles in boiling salted water according to package instructions.
Heat the oil in a coated pan. Leave the bacon in it until crispy, take it out. Put onion cubes into the pan, fry for 1-2 minutes. Dust onion with flour and sauté. Deglaze with stock and whipped cream, bring to the boil and simmer for about 2 minutes.
Add the bacon and tomatoes to the sauce and warm it up. Season with salt, pepper and lemon juice. Halve the avocado and remove the stone. Remove the flesh from the skin and cut into pieces. Drain the pasta, put it back into the pot with the avocado, spring onions and the sauce, mix everything carefully.
Arrange on plates.