Self Crusting Spinach and Tuna Quiche

1 lge Onion, 2 cloves Garlic, 1 tblsp Butter, 3 Eggs, 3/4 tsp Salt, 1 cup Milk, 1/2 cup Self-Raising Flour,  1 185g can Tuna in Spring Water, cooked Spinach, 1 cup grated Cheese, any other cooked veges if you like.
cook the onion and garlic in the butter until soft allow to cool, put eggs ,milk,and salt in a large bowl whisk with a fork, add the onion and garlic when cool add flour and combine,add the tuna, cheese, spinach  and any other vegs, pour into prepared tin and garnish with sliced tomatoes,

Bake at 220c for 20 to 30 mins until set in the centre.