1Rinse the sardines under cold water and pat them dry with paper towels.
Heat a non-stick pan over medium heat and add the sardines. Cook for about 3-4 minutes on each side until they are golden brown and cooked through. Remove from the pan and set aside.
In the same pan, add the chopped onion and stir fry for 2-3 minutes until it becomes translucent.
Add the stir fry vegetables to the pan and cook for another 5-7 minutes until they are tender but still crisp.
Chop the tomatoes and add them to the pan. Cook for an additional 2-3 minutes until they soften.
Squeeze the juice of one lemon over the vegetables and stir well.
Return the sardines to the pan and gently mix them with the vegetables.
Cook for another 2 minutes to allow the flavors to meld together.
Serve the Sardine and Vegetable Medley hot, garnished with lemon slices if desired.