Preheat oven to 350°F (180°C).

Heat a little olive oil in a large saucepan over medium heat. Sauté the onions until they are soft and golden. Add the peppers, zucchini, mushrooms, and cherry tomatoes and sauté for 10–15 minutes until all vegetables are soft. Stir in salt and remove from heat.

In a bowl, combine tomato paste and sour cream and set aside 1/3 cup. Combine vegetables and remaining tomato paste mixture and start layering your lasagna: Pour the reserved 1/3 cup of sauce into the bottom of a 9×13-inch pan. Arrange 3–4 raw noodles over the sauce. 

Spread 1/3 of the vegetable mixture over the noodles and sprinkle some cheese over it.

Repeat twice noodles, vegetables, and cheese, ending with a layer of noodles. 

Sprinkle remaining shredded cheese over the last layer of noodles.

Cover tightly with aluminium foil. Bake for 45–60 minutes.