Sauté the onion and garlic until soft and fragrant then set aside to cool.
Preheat the oven to 180C.
In large bowl mix the zucchini flesh, rice, herbs and season to taste. Add the cooled onion and garlic and mix well.
Take the zucchinis, salt their hollowed cores slightly and stuff them with the rice filling but not fully, because rice needs room to expand.
Arrange the carrot pieces on the bottom of a baking dish with a lid. Then place the zucchinis on top of them and pour around the stock until it reaches halfway up the zucchinis.
Put lid on or cover them with alfoil and pop in the oven to cook about 30’ - 40’ minutes. Check them halfway to see how long the rice needs to fully cook.
Once food is ready, beat the egg until almost fluffy (you want a semi - runny consistency), add the lemon juice and with a ladle take some of the cooked stock. Whisking add the hot liquid to temper the egg until you have used most of it.
Drizzle all the sauce, over the zucchinis and serve with crusty bread and a nice cool white wine.