Preheat the oven to 170°C.
Bring a large pan of water to the boil. Add the silverbeet and return to the boil for 2 minutes.
Drain and squeeze excess moisture from the cooked silverbeet.
Heat the olive oil in a frying pan. Add the onion and sauté for 2 - 3 minutes.
Transfer the onion to a bowl with the silverbeet, shallots, mint, and cheese.
Separate the eggs into two separate bowls. Beat the egg yolks and mix them into the bowl with the silverbeet. Stir through the lemon juice and season with black pepper.
Use an electric beater to mix the egg whites until stiff. Fold through the silverbeet mixture.
Line six, 1-cup ramekins with baking paper and spoon the mixture into each dish.
Place on a baking tray in the oven to bake to 35 to 40 minutes or until set.
Serve each frittata with 2 rye crackers, a teaspoon of tahini and fresh tomato