Mix all of the meatball ingredients in a bowl with your hands. Squash it all together but don’t overmix as this will make the meatballs tough. Shape the meatballs into 12 balls – the size of a golfball – and place them on a baking tray. Bake in the oven for about 20 mins. Keep an eye on them toward the end of the cooking time and turn the oven down a little if they start going too dark.
Whilst the meatballs are cooking, make the sauce. Fry the onions and celery in the olive oil on a low heat for about 5 mins. Add the garlic and cook for a further minute.
Add the tinned tomatoes, tomato puree and let it bubble for 10 minutes until thickened.
Next colour the spaghetti. Take a small bowl or jug and add 120ml/1/2 cup of warm or cold water. Add the food colouring and stir. Add the spaghetti and stir until the spaghetti turns green. Carefully remove the spaghetti from the dye and give it a quick rinse under the tap to remove excess dye. Place in a bowl until ready to assemble the subs.
Now make the eyes. Place the olive slices on a chopping board and use the tip of a teaspoon to spread a tiny blob of tomato puree into the centre of each of the olive slices. Place one olive slice on top of each slice of radish. Repeat to make as many eyes as you like.
Place the subs on 4 plates. Spoon 2-3 tablespoons of the tomato sauce onto the base of each sub. Place 3 meatballs in each sub, and top with a few strands of spaghetti and another spoonful of the tomato sauce. Add one or two eyeballs to each meatball and serve!