Step 1

Preheat oven to 200°F. Line a baking tray with foil and place a baking rack (roast rack) on top.

Step 2

Place the rosemary, garlic and oil in a small food processor. Process until you have a paste.

Step 3

Mix the rosemary-garlic paste with the salt and pepper. Spread half of this spice paste over the beef roast.

Step 4

Heat a cast iron pan to medium-high heat. Coat the bottom of the pan with vegetable oil and allow it to heat up. When the oil is hot, sear the beef roast in the pan, 3 - 4 minutes per side, until you form a caramelized crust.

Step 5

Place the seared cut of roast on the roast rack and spread the other half of the spice paste on the roast.

Step 6

Insert the meat thermometer into the roast, and place it in the preheated oven. Set the temperature to the required done-ness (133°F - rare, 138°F - medium, 145°F - medium to well-done), and slow roast the beef until the meat reaches the right temperature (mine took 2 hr 45 minutes for a 134°F internal temperature).

Step 7

When the roast is cooked through, remove it from the oven and let it rest for about 20 - 30 minutes.

Step 8

OPTIONAL STEP to smoke the roast - place the slow roasted beef in an airtight, glass container. Using a hand-held smoker, create smoke with hickory wood chips. Fill the container with the smoke and close it immediately. Allow the smoke to infuse with the roast, until the smoke disappears. Repeat this process 2 - 3 more times, to add a delightful smokiness to  your roast.

Step 9

When ready to serve, slice very thinly and serve.

Step 10

Mix the dijonnaise and butter until you have a smooth paste. Add salt to taste. Set aside until needed.

Step 11

Spread the mustard butter on the lower half of the toasted buns.

Step 12

Top with thinly sliced slow roasted beef, followed by the caramelized onions and peach relish.

Step 13

Layer the salad leaves on top. Spread mayonnaise on the top half of the bread bun and serve with potato chips.