Preheat the oven to 425°F (220°C) and place a baking sheet inside.
Wash and scrub the baby potatoes thoroughly, pat dry.
Cut the baby potatoes in half or quarters for even cooking.
In a mixing bowl, whisk together Dijon mustard, whole-grain mustard, olive oil, garlic, salt, black pepper, paprika, thyme, rosemary, onion powder, honey, and lemon juice.
Add the cut potatoes to the bowl, toss to coat well with the marinade.
Let the coated potatoes sit in the marinade for 5–10 minutes.
Remove the preheated baking sheet from the oven, drizzle with olive oil.
Spread the marinated potatoes evenly with cut-sides down.
Roast for 20 minutes without stirring.
Flip the potatoes using a spatula, then roast for an additional 15–20 minutes until golden brown and tender.
Remove from the oven, sprinkle with flaky sea salt.
Garnish with fresh parsley and serve with lemon wedges.
Notes
Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in the oven at 375°F (190°C) for 10-15 minutes to restore crispiness.