Preheat the oven to 400°F (200°C).
Toss sweet potato slices with olive oil, smoked paprika, garlic powder, and salt.
Spread them on a baking sheet and roast for 12 minutes, flipping halfway through.
While they roast, heat a small skillet over medium heat and add olive oil.
Sauté garlic for 30 seconds, then add kale and red pepper flakes.
Cook for 2-3 minutes until wilted, then squeeze in lemon juice.
Toast the bread until golden brown.
Mix mashed avocado with lemon juice, salt, and black pepper.
Spread Dijon mustard (or hummus) on one slice of each sandwich.
Layer sweet potatoes, sautéed kale, and mashed avocado onto the bread.
Top with the second slice, press lightly, and slice in half.
Eat immediately, because waiting makes no sense.