Preheat a water bath to 131°F (55°C).
Mix together the spices in a bowl. Lightly salt and pepper the sirloin steak then sprinkle with the spices. Place meat in a sous vide bag then seal. Place the bag in the water bath and cook for 2 to 3 hours until heated through, or up to 10 hours until tenderized.
For more information on the cooking times you can read my detailed article which addresses why is there a range in sous vide cooking times.
Place the spinach in a bowl and set aside.
Heat the bacon over medium heat until the fat has rendered and the bacon is crispy, 15 to 20 minutes. Remove and discard all but about 1 tablespoon of the bacon fat. Add the shallots and garlic, cook until the shallots turn translucent, 3 to 5 minutes. Stir in the lemon juice then pour the mixture over the spinach and toss well to combine. Salt and pepper to taste.
Add the garlic and vinegar to a bowl and let sit for 5 minutes. Add the olive oil and whisk to combine. Toss the tomatoes and basil with the dressing.
Take the sous vide bag out of the water and remove the cooked steak. Dry it off thoroughly using paper towels or a dish cloth. Lightly salt the sirloin steak then quickly sear it for 1 to 2 minutes per side, until just browned, then remove from the heat. Cut the sirloin steak into slices.
Place a spoonful of the wilted spinach salad onto a plate. Lay several slices of the sirloin steak on the spinach, top with the tomatoes. Sprinkle with the basil, drizzle with olive oil, then serve.