Add tomatoes, basil, garlic, vinegar, oil, lemon zest, and oregano in a large bowl. Season with salt and pepper to taste and stir gently.
Remove lentils from the refrigerator and add to the bowl.
Add feta and gently stir until ingredients are combined.
Serve with baguette slices.
For best results, refrigerate for at least an hour or make this the night before and store in the fridge.