A well made roast beef sandwich can be a thing of magic. A perfectly rare roast beef sandwich is a thing of beauty.
The Best Roast Beef Sandwich
As far as picnic sandwiches go, the roast beef sandwich sits high in the pecking order of meat sandwiches – up there with chicken sandwiches of course.
Whether using leftover beef from a Sunday roast, opting for the ease of deli bought slices of perfectly rare beef, or roasting a loin solely for the purpose, there are so many versions of the classic roast beef sandwich.
For our version of the classic roast beef sandwich recipe fit for a picnic (the last bit is key, it must be portable and manageable) we are putting a slight twist on the classic with the addition of gorgeously slow-roasted tomatoes (recipe below) and sticky-sweet caramelised onions.
What Bread to Use for A Perfect Roast Beef Sandwich?
One of our key picnic tips for sandwiches is to always go with breads and fillings that will hold their own without going soggy. Slices of soft white bread are fine for a simple ham and cheese and a match made in heaven for cucumber sandwiches. But a bold sandwich such as roast beef, especially with the addition of slow-roasted tomatoes, needs sturdy bread to avoid soggy sandwich syndrome.
In this case, we have gone with crusty slices of homemade sourdough. Rye bread, baguettes, bagels and ciabattas are also strong candidates for a successful roast beef picnic sandwich. Breads that will soak up the flavours perfectly without becoming soggy.
What Cut of Beef is Best for Roast Beef Sandwiches?
While it is perfectly fine to use last night’s leftover rib roast, this delicious bottom round roast recipe is cooked low and slow and reverse seared. A great alternative oven roast, and perfect for roast beef sandwiches.
Deli’s nuanced in the art of the roast beef sandwich opt for a loin roast or eye round. These cuts are lean with the fat on the top as opposed to the marbling that makes your Sunday roast juicy and tender straight from the oven.
The marbled fat can solidify when cold creating tough veins in your slices. As a rule of thumb, these leaner cuts will be more tender and juicy when served cold. You can read more about the best cut of meat for a roast beef sandwich here.
We often opt for roasting a loin for the purpose. It also makes a great meal served hot and you have your perfectly cooked beef ready to slice the next day for your picnic sandwiches. Where possible, we cook the beef over the coals to get a nice crispy charred outer and a touch of smokiness. But cooking it in the oven is just fine and will have the same internal temperature for a perfect rare finish.
What is the Temperature for Rare Roast Beef?
Using an inexpensive meat thermometer will help you achieve the perfect doneness for your roast beef sandwich. The following is a guide for the internal temperature of roast beef doneness. These are the out of oven temperatures. Your beef should be left to rest after cooking. During this time, the meat will continue to cook (the internal temperature should rise). Resting also prevents the meat from drying out.
Roast Beef Cooking Temperatures
- Rare – 50°C |122°F
- Medium rare – 55°C |131°F
- Medium – 60°C |140°F
- Medium well – 65°C |149°F
- Well done – 70°C |158°F
How to Make a Roast Beef Sandwich for Your Next Picnic
Roast Beef Sandwich Recipe with Slow Roasted Tomatoes
- 4 oz 115gm rare roast beef, thinly sliced. More or less depending on your taste. (either leftover roast beef, pre roasted or deli bought slices)
- ½ small red onion - thinly sliced.
- 5-6 slow-roasted tomatoes cut in half and juice retained - recipe below
- 1 teaspoon wholegrain mustard
- Small handful washed watercress. (you can substitute with arugula or baby spinach.
- 2 slices of crusty sourdough or 1 small baguette - substitute bread of your choice
- Small dob of butter for onions. Butter for spreading on the sandwich optional.
- Olive oil with a small drizzle of balsamic vinegar for cooking the onions
- Place the thinly sliced onion in a frying pan with a small dob of butter and a drizzle of olive oil. Cook on medium heat stirring often being careful to sweat the onions not burn them.
- As the onions soften, add a small drizzle of balsamic vinegar and continue to stir (the balsamic will help the onions into a nice sweet jam-like consistency) Cook until the onions are soft and caramelised.
- Spread the whole grain mustard on one slice of the bread, layer with slices of roast beef and top with the caramelised onion.
- Top with watercress and roasted tomato halves (as per this recipe also shown below). Drizzle with any of the tomato juice before topping with the other slice of bread.
- Wrap tightly for packing in the hamper or picnic backpack. You may wish to cut in half before wrapping if you won't have an appropriately sharp knife in your picnic kit.
- Feel free to swap the greens for other robust dark greens such as spinach or arugula.
- If you like cheese on your roast beef sandwich, opt for a strong sharp cheese such as aged cheddar.
- Switch mustard for blue cheese for a different spin. I doubt both would be very nice so one or the other.
See the full post on how to make slow-roasted tomatoes for more notes and tips on using and storing roasted vine tomatoes.