Tip the bread mix into a bowl then rub in the oil and tomato purée until the mixture resembles breadcrumbs. Pour in 310ml lukewarm water and mix to a dough, then transfer to a floured surface. Knead for 10 minutes until the dough springs back to the touch. Place in a greased bowl, cover with cling film and leave in a warm place to rise for about 1 hour.
Preheat the oven to 200°C, fan 180°C, gas 6. Divide the dough into 12 equal balls. Roll 4 of the balls together then divide into 2 – so you’ll have 2 large and 8 small dough balls.
To make a tortoise, shape 1⁄3 of a dough ball into 5 smaller balls to form a head and 4 feet. Shape the remaining 2⁄3 into a round body, flatten the top slightly and put on a greaseproof paper-lined baking tray. Press the head and feet into the body and use a knife to score a criss-cross pattern into the top of each ‘shell’. Repeat so you have 2 large and 8 small tortoises.
Brush with the milk then scatter over the sesame seeds and cheese. Press 2 nigella seeds onto each head for eyes and bake for 15 minutes until golden. Serve on a bed of lettuce ‘grass’; or make into fun tomato salad sandwiches.