One-pan sausage, egg and baked bean stew

SERVES 4

Sunflower oil, for frying 450g packet beef sausages 1 onion, thinly sliced 1 garlic 10ml (2 tsp) mild mustard 400g tin chopped tomatoes 180ml (¾ cup) beef stock 410g tin baked beans in tomato sauce 2 handfuls baby spinach Salt and pepper 4 eggs