Brush your lemon slices with a little drizzle of olive oil and roast in the oven for 10 minutes.
In a medium bowl, mix together the olive oil, roasted lemon slices, chile (if using), herbs and peppercorns. Gently fold in the feta next and transfer to a large glass jar - if the feta isn't completely submerged - add more olive oil. Seal and refrigerate for at least 24 hours. The longer it sits the better it will taste. REMOVE THE JAR FROM YOUR FRIDGE 1/2 AN HOUR BEFORE YOU WANT TO USE IT TO RETURN TO LIQUID FORM.
Serve with bread, salad, roasted veggies, pasta or as an appetizer.
Also, when done with the feta, you can use the leftover oil on your salads.
Notes
* The serrano chile gets the dish to a very spicy level since they marinate and melt together. I suggest you skip it if you are not a super spicy lover!This will keep in your fridge for 2-3 weeks as long as its in a tight fitted lid, glass jar and the feta is submerged in oil.