Tear 100 g stale bread into pieces and blend it into fine breadcrumbs.

Combine the breadcrumbs, 100 g all-purpose flour, a pinch of salt, and 100 ml water in a mixing bowl.

Knead the mixture into a firm dough and set it aside.

Place 200 g tomatoes, 3 tsp green pesto, salt, black pepper, and lemon juice in a saucepan.

Simmer the tomato sauce over medium heat for 10 min, stirring occasionally.

Bring a saucepan of salted water to a boil while the sauce simmers.

Cut the dough directly into small pasta pieces over the boiling water using kitchen scissors.

Cook the pasta until the pieces float to the surface, about 2 to 4 min.

Reserve 30 ml pasta cooking water and drain the cooked pasta.

Stir the drained pasta and reserved pasta cooking water into the tomato sauce.