Higuera Street and the blocks immediately surrounding it concentrate most of SLO's restaurants within easy walking distance of each other. The range is good: Mexican and Cal-Mex, pizza, sushi, Thai, American comfort food, wine bars, and a few spots that resist categorization. Prices are reasonable by California standards — the presence of Cal Poly students keeps things somewhat grounded.
The strip between Osos and Garden Streets is the densest stretch. Most restaurants have outdoor seating that works well in good weather, which in SLO means most of the year. On Thursday evenings the street closes and the atmosphere shifts from restaurant row to block party, but on other nights the choice is more manageable and you can walk both sides and pick based on what looks right.
Several spots are worth noting: Firestone Grill at 1001 Higuera is a SLO institution for its Santa Maria-style BBQ, a local regional specialty involving red oak-fired tri-tip. Novo Restaurant at 726 Higuera has a creekside deck that's one of the better outdoor dining situations in downtown. For a quick local lunch, the Gus's Grocery chain started in SLO and has several locations that do good sandwiches.