Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Dice the red potatoes into small 1/2-inch cubes and toss them in a bowl with 2 grams of olive oil, half the sea salt, and half the black pepper.
Spread the potatoes in a single layer on the baking sheet and roast for 15 minutes to give them a head start.
While the potatoes roast, whisk together the Dijon mustard, dried oregano, and dried thyme in a small ramekin.
Pat the salmon fillet dry with a paper towel and spread the mustard-herb mixture evenly over the top surface.
Toss the broccoli florets with the remaining 2 grams of olive oil and a pinch of salt.
Remove the baking sheet from the oven, push the potatoes to one side, and place the salmon fillet and broccoli on the other side.
Return the sheet to the oven and roast for another 10 to 12 minutes until the salmon is opaque and the broccoli is tender-crisp.
Prepare the side salad by combining the spring mix, halved cherry tomatoes, sliced celery, and olives in a bowl, then drizzle with fresh lemon juice.
Serve the herb-crusted salmon alongside the roasted potatoes and broccoli, with the fresh garden salad on the side.