Heat 2 tsp olive oil in a large skillet or sauté pan on medium-high heat until shimmery. Wiggle the pan a bit so that oil coats the entire bottom.
Add the ½ large onion, 3 medium carrots, 3 garlic cloves, ¾ tsp chopped fresh rosemary, ¼ tsp salt, and 3-4 grinds of fresh black pepper. Cook 5 minutes, stirring occasionally, until onions are slightly translucent but still opaque enough to hold their shape, and carrots are "al dente." (Not crisp, but still firm to the bite!)
Serve garnished with sprigs of fresh rosemary if you have them.
Notes
Variations: Instead of rosemary, try:
sage (¾ tsp chopped fresh or ¼ tsp crushed dried), or
a pinch of nutmeg, or
1 tsp lemon zest, 2 tsp fresh parsley (add both in the last minute of cooking), and then season to taste with lemon juice