Wash all vegetables thoroughly. Peel carrots and cut on a bias into 1/4-inch thick slices (about 2 cups). Trim broccoli into florets, keeping sizes roughly uniform (about 2 cups). Slice zucchini and yellow squash into 1/4-inch half-moons (about 1 cup each). Core and seed the red bell pepper, then cut into 3/4-inch pieces (about 1 cup). Slice red onion into thin wedges (about 1/2 cup).

Cook

Sauté aromatics

Heat a large skillet or sauté pan over medium heat. Add 2 tablespoons olive oil and 1 tablespoon butter. When butter foams and oil shimmers, add the minced garlic and sauté 30–45 seconds until fragrant, stirring to prevent burning.

Add denser vegetables

Add the carrot slices and red onion wedges to the pan. Season with 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. Cook, stirring occasionally, for 4–5 minutes until carrots begin to soften and onion becomes translucent.

Add remaining vegetables

Add broccoli florets, red bell pepper, zucchini, and yellow squash. Drizzle the remaining 1 tablespoon olive oil over the vegetables, sprinkle the remaining 1/2 teaspoon salt, 1/4 teaspoon black pepper, and 1/4 teaspoon red pepper flakes. Stir to combine and cook for 5–7 minutes, stirring every 1–2 minutes so vegetables brown lightly but retain some bite. If pan becomes dry, add 1–2 tablespoons water and cover for 1–2 minutes to create steam and finish cooking.

Finish with herbs and acid

Remove the pan from heat. Stir in the fresh thyme leaves, chopped parsley (reserve a small pinch for garnish), and 1 tablespoon lemon juice. Taste and adjust seasoning with additional salt or pepper if needed.

Serve

Transfer vegetables to a serving dish. If using, sprinkle toasted sliced almonds and grated Parmesan over the top. Drizzle a little extra-virgin olive oil or an additional squeeze of lemon to taste. Serve warm as a side dish.