Preheat oven to 180°C FAN/ 350°F
Trim the green end off of your leeks, then slice lengthwise through the middle to slice the leek in half.
Holding onto the root end of the leek, wash the leek downwards so that any dirt washes out. Once thoroughly rinsed, slice off the very end.
To an oven-safe pan (I used stainless steel), add the butter and olive oil. Heat over a low/medium heat. Once melted, add your leeks, facing down into the pan.
Leave to gently brown for around 8 minutes over a medium/low heat.
Next, rotate the leeks so that they’re facing up. To your veg/chicken stock, mix the minced garlic and dried tarragon. Pour into the pan and season with salt and pepper.
Pop in the oven for 20-25 minutes, or until fork tender. Check half way through - if they’re taking on too much colour, cover with foil for the remaining cook time.
Serve up and enjoy!